大体积混凝土温度应力与温度控制(精装)

2.2.1 Surface Conductance β 16
2.2.2 Computation of the Effect of Superficial Thermal Insulation 17
2.3 Air Temperature 19
2.3.1 Annual Variation of Air Temperature 19
2.3.2 Cold Wave 19
2.4 Temperature Increments due to Sunshine 20
2.4.1 Sun Radiation on Horizontal Surface 20
2.4.2 Temperature Increment of the Dam Surface due to Sunshine 22
2.4.3 Influence of Sunshine on the Temperature of Horizontal Lift Surface 22
2.5 Estimation of Water Temperature in Reservoir 25
2.6 Numerical Computation of Water Temperature in Reservoir 28
2.7 Thermal Properties of Concrete 29
2.8 Heat of Hydration of Cement and the Adiabatic Temperature Rise of Concrete 31
2.8.1 Heat of Hydration of Cement 31
2.8.2 Adiabatic Temperature Rise of Concrete 32
2.9 Temperature on the Surface of Dam 35
2.10 The Autogenous Deformation of Concrete 36
2.11 Semi-Mature Age of Concrete 36
2.11.1 Method for Determining the Semi-Mature Age of Concrete 37
2.11.2 Formulas for Computing the Semi-Mature Age of Concrete 38
2.11.3 Meaning of Semi-Mature Age in Engineering 40
2.11.4 Example of the Influence of Semi-Mature Age 40
2.11.5 Measures for Adjusting the Semi-Mature Ages of Concrete 41
2.11.6 Conclusions 42
2.12 Deformation of Concrete Caused by Change of Humidity 42
2.13 Coefficients of Thermal Expansion of Concrete 43
2.14 Solution of Temperature Field by Finite Difference Method 44
3 Temperature Field in the Operation Period of a Massive Concrete Structure 49
3.1 Depth of Influence of the Variation of Exterior Temperature in the Operation Period 49
3.1.1 Depth of Influence of Variation of Water Temperature 49
3.1.2 Depth of Influence of Variation of Air Temperature 50
3.2 Variation of Concrete Temperature from the Beginning of Construction to the Period of Operation 53
3.3 Steady Temperature Field of Concrete Dams 54
4 Placing Temperature and Temperature Rise of Concrete Lift due to Hydration Heat of Cement 57
4.1 Mixing Temperature of Concrete—T0 57
4.2 The Forming Temperature of Concrete T1 58
4.3 Placing Temperature of Concrete Tp 60
4.4 Theoretical Solution of Temperature Rise of Concrete Lift due to Hydration Heat of Cement 62
4.4.1 Temperature Rise due to Hydration Heat in Concrete
Lift with First Kind of Boundary Condition 4.4.2 Temperature Rise due to Hydration Heat in Concrete
Lift with Third Kind of Boundary Condition 64
4.4.3 Temperature Rise due to Hydration Heat with Adiabatic Temperature Rise Expressed by Compound Exponentials 66
4.5 Theoretical Solution of Temperature Field of Concrete Lift due to Simultaneous Action of Natural Cooling and Pipe Cooling 67
4.6 Temperature Field in Concrete Lift Computed by Finite Difference Method 69
4.6.1 Temperature Field in Concrete Lift due to Hydration Heat Computed by Finite Difference Method 69
4.6.2 Temperature Field due to Hydration Heat in Concrete Lift with Cooling Pipe Computed by Finite Difference Method 70
4.7 Practical Method for Computing Temperature Field in Construction Period of Concrete Dams 72
4.7.1 Practical Method for Computing Temperature Field in Concrete Lift without Pipe Cooling 74
4.7.2 Influence of the Placing Temperature Tp of the New Concrete 75
4.7.3 Practical Method for Computing Temperature in Concrete Lift without Pipe Cooling 77
4.7.4 Practical Method for Computing Temperature Field in Concrete Lift with Pipe Cooling 77
4.7.5 Practical Treatment of Boundary Condition on the Top Surface 80
5 Natural Cooling of Mass Concrete 83
5.1 Cooling of Semi-Infinite Solid, Third Kind of Boundary Condition 83
5.2 Cooling of a Slab with First Kind of Boundary Condition 85
5.3 Cooling of a Slab with Third Kind of Boundary Condition 89
5.4 Temperature in a Concrete Slab with Harmonic Surface Temperature 91
5.4.1 Concrete Slab with Zero Initial Temperature and Harmonic Surface Temperature 91
5.4.2 Concrete Slab, Initial Temperature T0, Harmonic Surface Temperature 94
5.5 Temperature in a Slab with Arbitrary External Temperature 98
5.6 Cooling of Mass Concrete in Two and Three Directions, Theorem of Product 101
6 Stress-Strain Relation and Analysis of Viscoelastic Stress of Mass Concrete 105
6.1 Stress-Strain Relation of Concrete 105
6.1.1 Strain of Concrete due to Constant Stress 105
6.1.2 Strain of Concrete due to Variable Stress 107
6.1.3 Modulus of Elasticity and Creep of Concrete 107
6.1.4 Lateral Strain and Poisson’s Ratio of Concrete 110
6.2 Stress Relaxation of Concrete 111
6.2.1 Stress Relaxation of Concrete Subjected to Constant Strain 111
6.2.2 Method for Computing the Relaxation Coefficient from Creep of Concrete 112
6.2.3 Formulas for Relaxation Coefficient 114
6.3 Modulus of Elasticity, Unit Creep, and Relaxation Coefficient of Concrete for Preliminary Analysis 115
6.4 Two Theorems About the Influence of Creep on the Stresses and Deformations of Concrete Structures 115
6.5 Classification of Massive Concrete Structures and Method of Analysis 117
6.6 Method of Equivalent Modulus for Analyzing Stresses in Matured Concrete due to Harmonic Variation of Temperature 117
7 Thermal Stresses in Fixed Slab or Free Slab 121
7.1 Thermal Stresses in Fixed Slab 121
7.1.1 Computation of the Temperature Field 121
7.1.2 The Elastic Thermal Stress 121
7.1.3 The Viscoelastic Thermal Stresses 123
7.1.4 The Thermal Stresses in Fixed Slab Due to Hydration Heat of Cement 123
7.2 Method for Computing Thermal Stresses in a Free Slab 126
7.2.1 Elastic Thermal Stress in a Free Slab When the Modulus of Elasticity is Constant 126
7.2.2 Viscoelastic Thermal Stress in a Free Slab Considering the Influence of Age 128
7.3 Thermal Stresses in Free Concrete Slab due to Hydration Heat of Cement 129
7.4 Thermal Stresses in Free Slabs with Periodically Varying Surface Temperature 129
7.4.1 The Temperature Field 129
7.4.2 The Viscoelastic Thermal Stresses 134
7.5 Thermal Stress in Free Slab with Third Kind of Boundary Condition and Periodically Varying Air Temperature 134
7.6 Thermal Stresses Due to Removing Forms 138
7.6.1 Stresses Due to Removing Forms of Infinite Slab 138
7.6.2 Stresses Due to Removing Forms of Semi-infinite Solid 139
7.6.3 Computing Thermal Stress Due to Removing Forms by Finite Element Method 141
8 Thermal Stresses in Concrete Beams on Elastic Foundation 143
8.1 Self-Thermal Stress in a Beam
8.2 Restraint Thermal Stress of Beam on Foundation of Semi-infinite Plane 145
8.2.1 Nonhomogeneous Beam on Elastic Foundation 145
8.2.2 Homogeneous Beam on Elastic Foundation 152
8.3 Restraint Stresses of Beam on Old Concrete Block 156
8.4 Approximate Analysis of Thermal Stresses in Thin Beam on Half-Plane Foundation 159
8.5 Thermal Stress on the Lateral Surface of Beam on Elastic Foundation 159
8.6 Thermal Stresses in Beam on Winkler Foundation 161
8.6.1 Restraint Stress of Beam in Pure Tension 161
8.6.2 Restraint Stress of Beam in Pure Bending 162
8.6.3 Restraint Stresses of Beam in Bending and Tension 163
8.6.4 Coefficients of Resistance of Foundation 165
8.6.5 Approximate Method for Beam on Winkler Foundation 167
8.6.6 Analysis of Effect of Restraint of Soil Foundation 167
8.7 Thermal Stresses in Beams on Elastic Foundation When Modulus of Elasticity of Concrete Varying with Time 169
9 Finite Element Method for Computing Temperature Field 171
9.1 Variational Principle for the Problem of Heat Conduction 171
9.1.1 Euler’s Equation 171
9.1.2 Variational Principle of Problem of Heat Conduction 172
9.2 Discretization of Continuous Body 174
9.3 Fundamental Equations for Solving Unsteady Temperature Field by FEM 174
9.4 Two-Dimensional Unsteady Temperature Field, Triangular Elements 178
9.5 Isoparametric Elements 180
9.5.1 Two-Dimensional Isoparametric Elements 180
9.5.2 Three-Dimensional Isoparametric Elements 182
9.6 Computing Examples of Unsteady Temperature Field 183
10 Finite Element Method for Computing the Viscoelastic Thermal Stresses of Massive Concrete Structures 185
10.1 FEM for Computing Elastic Thermal Stresses 185
10.1.1 Displacements of an Element 185
10.1.2 Strains of an Element 187
10.1.3 Stresses of an Element 188
10.1.4 Nodal Forces and Stiffness Matrix of an Element 189
10.1.5 Nodal Loads 190
10.1.6 Equilibrium Equation of Nodes and the Global Stiffness Matrix 191
10.1.7 Collection of FEM Formulas 191
10.2 Implicit Method for Solving Viscoelastic Stress-Strain Equation of Mass Concrete 192
10.2.1 Computing Increment of Strain 192
10.2.2 Relationship Between Stress Increment and Strain Increment for One-Directional Stress 196
10.2.3 Relationship Between Stress Increment and Strain Increment for Complex Stress State 197
10.3 Viscoelastic Thermal Stress Analysis of Concrete Structure 199
10.4 Compound Element 202
10.5 Method of Different Time Increments in Different Regions 203
11 Stresses due to Change of Air Temperature and Superficial Thermal Insulation 205
11.1 Superficial Thermal Stress due to Linear Variation of Air Temperature During Cold Wave 205
11.2 Superficial Thermal Insulation, Harmonic Variation of Air Temperature, One-Dimensional Heat Flow 208
11.2.1 Superficial Thermal Insulation, Daily Variation of Air Temperature, One-Dimensional Heat Flow 208
11.2.2 Superficial Thermal Insulation for Cold Wave, One-Dimensional Heat Flow 211
11.2.3 Superficial Thermal Insulation, Temperature Drop in Winter, One-Dimensional Heat Flow 214
11.3 Superficial Thermal Insulation, Harmonic Variation of Air Temperature, Two-Dimensional Heat Flow 216
11.3.1 Two-Dimensional Heat Flow, Thermal Insulation for Daily Variation of Air Temperature 216
11.3.2 Two-Dimensional Heat Flow, Thermal Insulation for Cold Wave 217
11.3.3 Two-Dimensional Heat Flow, the Superficial Thermal Insulation During Winter 220
11.4 Thermal Stresses in Concrete Block During Winter and Supercritical Thermal Insulation 220
11.4.1 Superficial Thermal Stresses During Winter 220
11.4.2 Computation of Superficial Thermal Insulation 223
11.4.3 Determining the Thickness of Superficial Thermal Insulation Plate 225
11.5 Comprehensive Analysis of Effect of Superficial Thermal Insulation for Variation of Air Temperature 226
11.6 The Necessity of Long Time Thermal Insulation for Important Concrete Surface 227
11.7 Materials for Superficial Thermal Insulation 230
11.7.1 Foamed Polystyrene Plate 230
11.7.2 Foamed Polythene Wadded Quilt 230
11.7.3 Polyurethane Foamed Coating 231
11.7.4 Compound Permanent Insulation Plate 231
11.7.5 Permanent Thermal Insulation and Anti-Seepage Plate 231
11.7.6 Straw Bag 232
11.7.7 Sand Layer 232
11.7.8 Requirements of Thermal Insulation for Different
Concrete Surfaces 233
12 Thermal Stresses in Massive Concrete Blocks 235
12.1 Thermal Stresses of Concrete Block on Elastic Foundation
due to Uniform Cooling 235
12.1.1 Thermal Stresses of Block on Horizontal Foundation 235
12.1.2 Danger of Cracking of Thin Block with Long Time of
Cooling 238
12.1.3 Concrete Block on Inclined Foundation 238
12.2 Influence Lines of Thermal Stress in Concrete Block 239
12.3 Influence of Height of Cooling Region on Thermal Stresses 243
12.3.1 Influence of Height of Cooling Region on Elastic Thermal
Stresses 243
12.3.2 Influence of Height of Cooling Region on the Viscoelastic
Thermal Stresses 245
12.4 Influence of Height of Cooling Region on Opening of Contraction
Joints 246
12.5 Two Kinds of Temperature Difference Between Upper and
Lower Parts of Block 247
12.6 Two Principles for Temperature Control and the Allowable
Temperature Differences of Mass Concrete on Rock
Foundation 249
12.6.1 Stresses due to Stepwise Temperature Difference 249
12.6.2 Positive Stepwise Temperature Difference and the
First Principle About the Control of Temperature
Difference of Concrete on Rock Foundation 252
12.6.3 Negative Stepwise Temperature Difference and the
Second Principle About the Control of Temperature
Difference of Concrete on Rock Foundation 255
12.6.4 Stresses due to Multi-Stepwise Temperature Difference 255
12.6.5 Viscoelastic Thermal Stresses Simulating Process of
Construction of Multilayer Concrete Block on Rock
Foundation 256
12.7 Approximate Formula for Thermal Stress in Concrete Block
on Rock Foundation in Construction Period 259
12.8 Influence of Length of Concrete Block on the Thermal Stress 260
12.8.1 Influence of Length of Concrete Block on the Thermal
Stress due to Temperature Difference Between the Upper
and Lower Parts 260
12.8.2 Influence of Joint Spacing on the Thermal Stress
due to Annual Variation of Temperature 262
12.9 Danger of Cracking due to Over-precooling of Concrete 263

12.10 Thermal Stresses in Concrete Blocks Standing Side by Side 265
12.11 Equivalent Temperature Rise due to Self-Weight of Concrete 265
13 Thermal Stresses in Concrete Gravity Dams 267
13.1 Thermal Stresses in Gravity Dams due to Restraint of Foundation 267
13.2 Influence of Longitudinal Joints on Thermal Stress in Gravity Dam 270
13.3 The Temperatures and Stresses in a Gravity Dam Without Longitudinal Joint 271
13.4 Gravity Dam with Longitudinal Crack 271
13.5 Deep Crack on the Upstream Face of Gravity Dam 272
13.6 Opening of Longitudinal Joint of Gravity Dam in the Period of Operation 273
13.7 Thermal Stresses of Gravity Dams in Severe Cold Region 274
13.7.1 Peculiarity of Thermal Stresses of Gravity Dam in Severe Cold Region 274
13.7.2 Horizontal Cracks and Upstream Face Cracks 275
13.7.3 Measures for Preventing Cracking of Gravity Dam in Severe Cold Region 278
13.8 Thermal Stresses due to Heightening of Gravity Dam 279
13.9 Technical Measures to Reduce the Thermal Stress due to Heightening of Gravity Dam 284
14 Thermal Stresses in Concrete Arch Dams 287
14.1 Introduction 287
14.1.1 Self-Thermal Stresses of Arch Dam 287
14.1.2 Three Characteristic Temperature Fields in Arch Dam 288
14.1.3 Temperature Loading on Arch Dams 289
14.2 Temperature Loading on Arch Dam for Constant Water Level 289
14.2.1 Formulas for Tm2 and Td2 290
14.2.2 Physical Meaning of the Equivalent Linear Temperature 291
14.3 Temperature Loading on Arch Dam for Variable Water Level 292
14.3.1 Computation of Surface Temperature of Dam for Variable Water Level 292
14.3.2 Temperature Loading on Arch Dam for Variable Water Level 294
14.4 Temperature Loadings on Arch Dams in Cold Region with Superficial Thermal Insulation Layer 297
14.4.1 Tm1 and Td1 for the Annual Mean Temperature Field T1(x) 297
14.4.2 Exact Solution of Tm2 and Td2 for the Yearly Varying Temperature Field T2(x,T) 300
14.4.3 Approximate Solution of Tm2 and Td2 for the Yearly Varying Temperature Field T2(x,τ) 304
14.5 Measures for Reducing Temperature Loadings of Arch Dam 305
14.5.1 Optimizing Grouting Temperature 306
14.5.2 Superficial Thermal Insulation 306
14.6 Temperature Control of RCC Arch Dams 306
14.6.1 RCC Arch Dams without Transverse Joint 306
14.6.2 RCC Arch Dam with Transverse Joints 307
14.7 Observed Thermal Stresses and Deformations of Arch Dams 308
15 Thermal Stresses in Docks, Locks, and Sluices 313
15.1 Self-Thermal Stresses in Walls of Docks and Piers of Sluices 313
15.2 Restraint Stress in the Wall of Dock 314
15.2.1 General Theory for the Restraint Stress in the Wall of Dock 314
15.2.2 Computation for Wide Bottom Plate 317
15.2.3 Computation for Bottom Plate with Moderate Width 320
15.3 Restraint Stress in the Piers of Sluices 321
15.4 Restraint Stress in the Wall of Dock or the Pier of Sluice on Narrow Bottom Plate 323
15.5 Simplified Computing Method 325
15.5.1 T Beam 325
15.5.2 Simplified Computation of Thermal Stresses in Dock 327
15.5.3 Simplified Method for Thermal Stresses in Sluices 328
15.5.4 Simplified Method for E(y, τ) Varying with Age τ 329
15.6 Thermal Stresses in a Sluice by FEM 329
15.6.1 Thermal Stress due to Hydration Heat of Cement in Construction Period 329
16 Simulation Analysis, Dynamic Temperature Control, Numerical Monitoring, and Model Test of Thermal Stresses in Massive Concrete Structures 333
16.1 Full Course Simulation Analysis of Concrete Dams 333
16.2 Dynamic Temperature Control and Decision Support System of Concrete Dam 334
16.3 Numerical Monitoring of Concrete Dams 335
16.3.1 The Drawbacks of Instrumental Monitoring 336
16.3.2 Numerical Monitoring 336
16.3.3 The Important Functions of Numerical Monitoring 336
16.4 Model Test of Temperature and Stress Fields of Massive Concrete Structures 337
17 Pipe Cooling of Mass Concrete 341
17.1 Introduction 341
17.2 Plane Temperature Field of Pipe Cooling in Late Stage 342
17.2.1 Plane Temperature Field of Concrete Cooled by Nonmetal Pipe in Late Stage 342
17.2.2 Plane Temperature Field of Concrete Cooled by Metal Pipe in Late Stage 346
17.3 Spatial Temperature Field of Pipe Cooling in Late Stage 348
17.3.1 Method of Solution of the Spatial Problem of Pipe Cooling 348
17.3.2 Spatial Cooling of Concrete by Metal Pipe in Late Stage 352
17.3.3 Spatial Cooling of Concrete by Nonmetal Pipe in Late Stage 356
17.4 Temperature Field of Pipe Cooling in Early Stage 358
17.4.1 Plane Problem of Pipe Cooling of Early Stage 358
17.4.2 Spatial Problem of Pipe Cooling of Late Stage 360
17.5 Practical Formulas for Pipe Cooling of Mass Concrete 362
17.5.1 Mean Temperature of Concrete Cylinder with Length L 362
17.5.2 Mean Temperature of the Cross Section of Concrete Cylinder 364
17.5.3 Time of Cooling 365
17.5.4 Formula for Water Temperature 366
17.6 Equivalent Equation of Heat Conduction Considering Effect of Pipe Cooling 367
17.6.1 Temperature Variation of Concrete with Insulated Surface and Cooling Pipe 367
17.6.2 Equivalent Equation of Heat Conduction Considering the Effect of Pipe Cooling 370
17.7 Theoretical Solution of the Elastocreeping Stresses Due to Pipe Cooling and Self-Restraint 371
17.7.1 The Elastic Thermal Stress Due to Self-Restraint 371
17.7.2 The Elastocreeping Thermal Stress Due to Self-Restraint 373
17.7.3 A Practical Formula for the Elastocreeping Thermal Stress Due to Self-Restraint 374
17.7.4 Reducing Thermal Stress by Multistage Cooling with Small Temperature Differences—Theoretical Solution 374
17.7.5 The Elastocreeping Self-Stress Due to Pipe Cooling and Hydration Heat of Cement 375
17.8 Numerical Analysis of Elastocreeping Self-Thermal Stress of Pipe Cooling 376
17.8.1 Computing Model 376
17.8.2 Elastocreeping Stresses in 60 Days Early Pipe Cooling 377
17.8.3 Elastocreeping Stresses in 20 Days Early Pipe Cooling 377
17.8.4 Elastocreeping Stresses in Late Pipe Cooling 377
17.8.5 New Method of Cooling—Multistep Early and Slow Cooling with Small Temperature Differences—Numerical Analysis 379
17.9 The FEM for Computing Temperatures and Stresses in Pipe Cooled Concrete 380
17.9.1 Pipe Cooling Temperature Field Solved Directly by FEM 380
17.9.2 Equivalent FEM for Computing the Temperatures and
Stresses in Mass Concrete Block with Cooling Pipe 382
17.9.3 Comparison Between the Direct Method and the Equivalent Method for Pipe Cooling 384
17.10 Three Principles for Pipe Cooling 384
17.11 Research on the Pattern of Early Pipe Cooling 386
17.12 Research on the Pattern of the Medium and the Late Cooling 387
17.12.1 The Influence of Temperature Gradient on the Thermal Stress 387
17.12.2 The Influence of Pipe Spacing on the Thermal Stress 389
17.12.3 The Influence of the Number of Stages of Pipe Cooling 389
17.13 Strengthen Cooling by Close Polythene Pipe 389
17.13.1 Effect of Cooling by Close Pipe 389
17.13.2 Influence of Cooling of Pipe with Small Spacing on the Thermal Stress 391
17.13.3 The Principle for Control of Pipe Spacing and Temperature Difference T0 2 Tw 394
17.14 Advantages and Disadvantages of Pipe Cooling 395
17.15 Superficial Thermal Insulation of Mass Concrete During Pipe Cooling in Hot Seasons 398
18 Precooling and Surface Cooling of Mass Concrete 401
18.1 Introduction 401
18.2 Getting Aggregates from Underground Gallery 402
18.3 Mixing with Cooled Water and Ice 403
18.4 Precooling of Aggregate 404
18.4.1 Precooling of Aggregate by Water Cooling 404
18.4.2 Precooling of Aggregate by Air Cooling 405
18.4.3 Precooling of Aggregate by Mixed Type of Water Spraying and Air Cooling 405
18.4.4 Precooling of Aggregate by Secondary Air Cooling 406
18.5 Cooling by Spraying Fog or Flowing Water over Top of the Concrete Block 406
18.5.1 Spraying Fog over Top of the Concrete Block 406
18.5.2 Cooling by Flowing Water over Top of the Concrete Block 408
19 Construction of Dam by MgO Concrete 409
19.1 MgO Concrete 409
19.2 Six Peculiarities of MgO Concrete Dams 410
19.2.1 Difference Between Indoor and Outdoor Expansive Deformation 410
19.2.2 Time Difference 412
19.2.3 Regional Difference 413
19.2.4 Dam Type Difference 414
19.2.5 Two Kinds of Temperature Difference 414
19.2.6 Dilatation Source Difference 414
19.3 The Calculation Model of the Expansive Deformation of MgO Concrete 415
19.3.1 The Calculation Model of the Expansive Deformation for Test Indoors 415
19.3.2 The Calculation of the Expansive Deformation of MgO Concrete of Dam Body Outdoors 415
19.3.3 The Incremental Calculation of the Autogenous Volume Deformation 416
19.4 The Application of MgO Concrete in Gravity Dams 416
19.4.1 Conventional Concrete Gravity Dams 416
19.5 The Application of MgO Concrete in Arch Dams 419
19.5.1 Arch Dams with Contraction Joints 419
19.5.2 Arch Dams without Contraction Joints, Time Difference 420
19.5.3 Example of Application of MgO Concrete, Sanjianghe MgO Concrete Arch Dam 423
20 Construction of Mass Concrete in Winter 425
20.1 Problems and Design Principles of Construction of Mass Concrete in Winter 425
20.1.1 Problems of Construction of Mass Concrete in Winter 425
20.1.2 Design Principles of Construction of Mass Concrete in Winter 426
20.2 Technical Measures of Construction of Mass Concrete in Winter 426
20.3 Calculation of Thermal Insulation of Mass Concrete Construction in Winter 428
21 Temperature Control of Concrete Dam in Cold Region 431
21.1 Climate Features of the Cold Region 431
21.2 Difficulties of Temperature Control of Concrete Dam in Cold Region 432
21.3 Temperature Control of Concrete Dam in Cold Region 433
22 Allowable Temperature Difference, Cooling Capacity, Inspection and Treatment of Cracks, and Administration of Temperature Control 439
22.1 Computational Formula for Concrete Crack Resistance 439
22.2 Laboratory Test of Crack Resistance of Concrete 441
22.3 The Difference of Tensile Properties Between Prototype Concrete and Laboratory Testing Sample 441
22.3.1 Coefficient b1 for Size and Screening Effect 441
22.3.2 Time Effect Coefficient b2
22.4 Reasonable Value for the Safety Factor of Crack Resistance 443
22.4.1 Theoretical Safety Factor of Crack Resistance 443
22.4.2 Practical Safety Factor of Concrete Crack Resistance 443
22.4.3 Safety Factors for Crack Resistance in Preliminary Design 445
22.5 Calculation of Allowable Temperature Difference and Ability of Superficial Thermal Insulation of Mass Concrete 447
22.5.1 General Formula for Allowable Temperature Difference and Superficial Thermal Insulation 447
22.5.2 Approximate Calculation of Allowable Temperature Difference and Insulation Ability 447
22.6 The Allowable Temperature Difference Adopted by Practical Concrete Dam Design Specifications 450
22.6.1 Regulations of Allowable Temperature Difference in Chinese Concrete Dam Design Specifications 450
22.6.2 The Requirement of Temperature Control in “Design Guideline of Roller Compacted Concrete Dam” of China 451
22.6.3 Temperature Control Regulation of Concrete Dam by
U.S. Bureau of Reclamation and U.S. Army Corps of Engineering 452
22.6.4 Temperature Control Requirements of Concrete Dam of Russia 453
22.7 Practical Examples for Temperature Control of Concrete Dams 453
22.7.1 Laxiwa Arch Dam 453
22.7.2 Toktogulskaya Gravity Dam 455
22.7.3 Dworshak Gravity Dam 459
22.8 Cooling Capacity 460
22.8.1 Calculation for the Total Cooling Capacity 460
22.8.2 Cooling Load for Different Cases 463
22.9 Inspection and Classification of Concrete Cracks 463
22.9.1 Inspection of Concrete Cracks 463
22.9.2 Classification of Cracks in Mass Concrete 464
22.10 Treatment of Concrete Cracks 464
22.10.1 Harm of Cracks 464
22.10.2 Environmental Condition of Cracks 465
22.10.3 Principle of Crack Treatment 465
22.10.4 Method of Crack Treatment 466
23 Key Principles for Temperature Control of Mass Concrete 469
23.1 Selection of the Form of Structure 469
23.2 Optimization of Concrete Material 470
23.3 Calculation of Crack Resistance of Concrete 470
23.4 Control of Temperature Difference of Mass Concrete 471
23.4.1 Temperature Difference Above Dam Foundation and Temperature Difference Between Upper and Lower Parts of Dam Block 471 23.4.2 Surface-Interior Temperature Difference 472
23.4.3 Maximum Temperature of Concrete 472
23.5 Analysis of Thermal Stress of Mass Concrete 472
23.5.1 Estimation of Thermal Stress 472
23.5.2 Primary Calculation of the Temperature Stress 473
23.5.3 Detailed Calculation of Thermal Stress 473
23.5.4 Whole Process Simulation Calculation 474
23.6 Dividing the Dam into Blocks 474
23.7 Temperature Control of Gravity Dam 475
23.8 Temperature Control of Arch Dam 476
23.9 Control of Placing Temperature of Mass Concrete 476
23.10 Pipe Cooling of Mass Concrete 477
23.11 Surface Thermal Insulation 477
23.12 Winter Construction 478
23.13 Conclusion 478
Appendix: Unit Conversion 479
References 481
Index 487

.　　Cracks in massive concrete structures, such as concrete dams, will reduce the safety, integrity, and durability of the structure. The repair of cracks in concrete dams is very difficult, e.g., a big crack developed in Norfork dam, the engineers had attempted to repair the dam by grouting, but due to the worry that the crack may develop further under the pressure of grouting, the crack was not repaired and the dam has been working with a big crack in the dam body; as a result, the safety and durability of the dam are reduced remarkably.
　　The successful construction of several concrete dams without crack in China is an important achievement in technical science in the world.
　　Due to the needs of flood control, irrigation, and hydropower, many concrete dams have been constructed in China in the past 60 years. At present the amount of concrete dams higher than 15 m in China is over 40% of those elsewhere and the three highest concrete dams in the world (Jingping 305 m, Xiaowan 295 m, Xiluodu 284 m) are in China. In the process of large-scale construction of concrete dams in China, besides learning abroad experiences, systematic research works had been carried out and new theory and new experiences were created; hence, the problem of cracking in mass concrete has been solved and several concrete dams without crack have been constructed in recent 10 years.
　　After graduating from university in 1951, the writer participated in the design and construction of the first three concrete dams in China (Fuzhiling dam, Meishang dam, and Xiang hongdian dam) in 1951-1957. Although some measures to prevent cracking had been adopted, cracks still appeared in these dams, which indicates that cracking of mass concrete is a complex problem. The writer began to research the problem in 1955 and published two papers in 1956 and 1957 which triggered research of thermal stress and temperature control of mass concrete in China.
　　In 1958, the writer was transferred to the China Institute of Water Resources and Hydropower Research where he was engaged in the research work of high concrete dams, particularly the thermal stresses and temperature control of concrete dams.
　　A vast amount of research works had been carried out under the direction of the writer for a series of important concrete dams in China, such as Three Gorges, Xiaowan, Longtan, Xiluodu, Sanmenxia, Liujiaxia, Xin’anjiang, and Gutian.
　　More than 120 papers had been published putting forward a series of new ideas, new calculating methods, and new technical measures, including (1) a new idea of “long time superficial thermal insulation together with comprehensive temperature control” which may prevent crack in mass concrete effectively, (2) methods for cal-culating the temperature field and thermal stresses in dams, docks, sluices, tunnels, concrete blocks, and beams on elastic foundations; (3) simulation thermal stress computation taking into account the influences of all the factors and simulating the process of construction; (4) method of back analysis for determining the practical thermal and mechanical properties of concrete from the observed results; (5) the new idea of numerical monitoring of mass concrete; (6) the new idea of semi-mature age of concrete; and (7) formulas for determining the water temperature in reservoirs and temperature loading of arch dams.
　　Hence, a perfect system of the theory of thermal stress and temperature control of mass concrete is established whereby several concrete dams without crack have been successfully constructed in China in the past 10 years, including the Sangianghe concrete arch dam and the third stage of the famous Three Gorges con-crete gravity dam and hence “no dam without crack” is no longer a problem.
　　The solution of the problem of cracking is an important achievement in the tech-nology of mass concrete.
　　More than 10 results of the author’s scientific research were adopted in the spe-cifications for design and construction of gravity dams, arch dams, docks, and mas-sive concrete structures in China.
　　In order to summarize the experiences, the author published the book Thermal Stresses and Temperature Control of Mass Concrete (in Chinese) in 1999.
　　The Information Center of the China Academy of Science published two statistics in 2011: (1) According to the number of quotations, the first 10 books of each profes-sion of China, Thermal Stresses and Temperature Control of Mass Concrete is one of the 10 most widely quoted books of civil engineering in China. (2) According to the number of quotations, the first 20 authors of scientific papers of each profession in China, the writer is the first one of the 20 most widely quoted authors of hydraulic engineering.
　　The author was awarded the China National Prize of Natural Science in 1982 for research work in thermal stresses in mass concrete, the China National Prize of Scientific Progress in 1988 for research work in the optimum design of arch dams, the China National Prize of Scientific Progress in 2000 for research work in simu-lating computation and thermal stresses, and the International Congress on Large Dams Honorary Member at Saint Petersburg in 2007.
　　Outside China there are two books on temperature control of mass concrete:
　　(1) US Bureau of Reclamation, Cooling of Concrete Dams, 1949, (2) Stuky A, Derron MH, Problemes Thermiques Poses Par La Construction des Barrages-Reservoirs, Lausanne, Sciences & Technique, 1957. Theoretical solutions and many graphs for determining the temperatures of concrete dams are given in these two books which are useful to engineers, but there is no method for computing the thermal stresses, no method for preventing crack except pipe cooling, no criterion for temperature control, no experiences for preventing cracks, particularly the suc-cessful experiences in China, thus, they are insufficient for engineers to design and construct mass concrete structures without crack.
　　A vast amount of mass concrete is placed in the world every year. How to pre-vent crack is still an important problem, thus Thermal Stresses and Temperature Control of Mass Concrete in English will be useful for engineers and professors of civil engineering.
　　In this book, consideration is given to both the theory and the practice. On one side, the methods for computing the temperature fields, thermal stresses, and the variation of temperatures and thermal stresses in various types of mass concrete structures are introduced in detail; on the other side, the technical measures to con-trol temperature and to prevent cracking, the criterion of temperature control and the experiences of practical engineering projects, particularly, the successful experi-ences in China in the construction of several concrete dams without crack, are described. A series of new ideas and new techniques, e.g., the idea of “long time superficial thermal insulation together with comprehensive temperature control,” MgO self-expansive concrete, etc., many useful methods, formulas, graphs, charts, and figures are given.
　　Apart from causing cracks, the change of temperature is an important and com-plex loading which has great influence on the stress state of concrete structures, particularly the arch dam. In the design and construction of mass concrete struc-tures, particular attention should be paid to thermal stress and temperature control. I hope the publication of this book will give useful help to the engineers engaged in the design and construction of mass concrete structures and the professors and students of the department of civil engineering of universities.
　　I am grateful to Mr. Wu Longshen, Miss Hao Wengqian, and Mrs. Li Yue for their help given to me in the preparation of this book.
　　Zhu Bofang
　　July 2013