Dissertation > Excellent graduate degree dissertation topics show

Experimental Study on Rock Mechanics Based on Deep Fracture in Typical Banks

Author: ZhangWenJu
Tutor: ZhaoQiHua
School: Chengdu University of Technology
Course: Geotechnical Engineering
Keywords: Deep cracks Ground stress field Zonation Unloading test Damage evolution
CLC: TU458.3
Type: PhD thesis
Year: 2009
Downloads: 346
Quote: 1
Read: Download Dissertation

Abstract


The southwest a topographic gradient zone is located in China, the region is very rich in hydropower resources, a series of construction of the proposed large-scale hydropower project is located in the region. Located in the eastern edge of the Qinghai-Tibet fault block tectonics of the region, the impact of continued uplift in the Qinghai-Tibet Plateau to nearly a hundred million years, the special complex geological environment conditions. Therefore, large, very large construction projects in these areas, there is urgent need for a series of constraints of engineering design, construction and operation of major engineering geological problems to be studied and solved, one of which is the problem of the bank slope deep cracks. As the main object of study, by choosing an Jinping, Dadu River, Shenxigou Shuangjiangkou large hydropower engineering survey revealed deep cracks research material, summarized the southwest region of the Tibetan Plateau stressed geological the prototype site investigation and geological processes and interpretation of the philosophical way of thinking, analysis, attention to the evolution of deep cracks in the occurrence of the natural slope of the formation geomechanical environment, the use of modern numerical simulation techniques and rock mechanics theory and method, the development and distribution of deep cracks and deformation and failure characteristics from the prototype geological research, numerical simulation inversion, rock mechanics testing, injury theoretical analysis of the four major aspects of integration, initially established a set of deep cracks in the basic framework of the research and technology methodology , made the following main results: (1) through typical bank slope deep cracks in the system, summarized the general characteristics of the fracture development, namely: ① cracks more than development in the bank slope rock mass above 70 ~ 120m from the trough; the ② crack was mostly between the the ribbon output, the rupture zone is relatively complete rock; ③ cracks very clean, almost no secondary folder mud; ④ fracture development with elevation increase and enhance overall, with the level of depth of increases weakened; ⑤ crack formation time overall with elevation increase and older, with the level of depth of increase becomes new; the steep dips structure ⑥ cracks along generally parallel with slope structural plane development;. (2) a comprehensive analysis of the geological environment of the the typical bank slope deep cracks generated, summarized proposed geological environmental conditions to be satisfied by the crack generation, namely: ① higher strain energy can be stored in the structural transformation process hard and brittle lithology conditions; ② conducive geological structures (such as wrinkled body) and structural conditions (lithology structure and tectonic fissures) strain energy storage and release; ③ as generalized \the the unloading springback Highlands stress conditions; ④ can lead to the condition of the rock mass strain energy intense crustal rapid uplift (ie the valley quickly under cut);. (3) that, accompanied by regional erosion and river valleys incised in the process of the formation and evolution of deep cracks in the valley (or superimposed the transverse valley) landforms, slope stress field changing adjustment, caused by the the bank slope rock mass internal pre-stored strain energy ( associated with the structural transformation of the extent and manner) intense to produce differences rebound unloading formed invading direction, is the supergene aging structure. (4) In accordance with the process of the formation and evolution of the bank slope geological bodies, determined the bank slope rock mass transformation model proposed bank slope rock mass inward by the slope of the table can be divided into supergene transformation supergene transformation of tectonic transformation of three with Table Health and transformation zone can be subdivided into the outside unloading Hera crack with the inside squeeze with supergene transformation with by the deep cracks in the band and with plate girder. And with rock mass stress, the sonic point load, fracture density, fracture aperture such as statistical analysis. (5) by the the typical bank slope measured geostress analysis showed that: the deep fracture development regions there is a big role of geological formations, is a high-stress zone (middle), the rock mass stress level of tectonic stress. (6) based on the typical bank slope measured stress values ??change with the level of depth of features on bank stress field zoning, upcoming bank slope rock mass stress divided into inward stress is reduced by the slope of the table increased stress, stress fluctuations, stress stabilization of the four band. In which the stress is reduced and the stress fluctuation band, and Slope unloading Dutch with the scope and deep range of fracture development control. The analysts believe that the stress fluctuations with the lower boundary is the depth of valley stress field, which statistics show, southwest valley areas depth of approximately 150 ~ 387m. (7) the bank slopes stress field distribution characteristics, and the the epigenetic transformation process of the bank slope rock mass is closely related to, based on the causes of the bank slope stress field inward slope table is divided into slope stress field zone, transition zone and tectonic stress three zones of the field area, and the transformation of the supergene supergene transformation and structural alteration of three with the corresponding districts stress distribution characteristics proposed slope stress field area mainly gravity stress transition zone is a tectonic stress field to gravitational stress field into the transition zone, the tectonic stress field area tectonic stress based point of view, and according to the measured maximum principal stress inclination verify this understanding with the depth of the change characteristics. (8) the use of modern numerical simulation technology to verify zoning characteristics of the bank slopes stress field and tectonic stress range of zonation; basic characteristics of the the bank slopes stress field evolution and the deep fractures formation process, and according to the geological processes cracks unit stress Mohr circle of changes in characteristics and explore the deep cracks in the generated time, draw near slope table and high elevation cracks, respectively, than the deep and low elevation crack formation during the earlier geological analysis is verified results. (9) deep cracks in the formation process of the actual stress changes state to test the design of the basis to carry out the different confining pressures under different unloading rates unloading rock mechanics contrast test, revealed by the test, the unloading conditions: ① with the destruction of the confining pressure increased specimen failure modes from tensional undermine the transition to shear failure, and at the same confining pressure, with the unloading rate increases, the sample proportion of tension fracture heavier; ② test samples showed a progressive failure characteristics, usually in the vicinity of the sample surface unloading of peeling sheet the general shear rupture surface in some sections of track tension fracture surface development and destruction with transtensional nature; ③ unloading the sample transverse strain the ε3 and volume strain εV greater impact into the unloading stage, the the ε3 change in gradient increased significantly, εV converted from compression deformation expansion; ④ majority of the specimen stress - strain curve after the peak there is a big drop, indicating that smaller specimen unloading destroy the plastic deformation and destruction of more sudden and brittle characteristics; ⑤ stress - strain curve peaks before the peak difference larger peak before the curve smoothing post-peak curve is uneven the peak sample after internal stress, strain prior to the peak of the distribution is more complex; ⑥ majority of specimens Stress - strain curve peaks was \conditions, confining pressure and at the same initial sample strength and deformation modulus of unloading rate increases is decreasing; ⑧ with the unloading rate increases, the the specimen shear strength parameters c value increase large φ value decreases, the rock shear strength parameters c values ??reduce the value of φ increased compared with the loading conditions; etc.. On the development and distribution of deep cracks and deformation and failure characteristics based on these test results, a reasonable explanation. (10) by assuming rock infinitesimal strength and its distribution, building damage evolution equation expressed in nominal stress and strain and the constitutive model and comparative analysis of damage evolution characteristics of rock under different experimental conditions that specimen by the Dutch process of damage evolution can be divided into three phases: the first phase of the experimental curves yield limit of the preceding paragraph corresponds to the segment of the stress - strain curve is approximately a straight line, rock infinitesimal mainly to elastic deformation, only a very few rock infinitesimal destruction, damage evolution from 0 was slowly increasing trend, the evolution of the slope of the curve slowly increasing; second phase of the test curve → residual strength segment corresponding yield limit, this section of the stress - strain curve is nonlinear, rock micro million was mainly dominated by plastic deformation, a large number of rock infinitesimal FAILURE damage evolution was a rapid increase in the trend of the evolution of the slope of the curve increases rapidly, and finally stabilized at a certain level remains unchanged; residual strength segment of the third stage of the test curve corresponding this section of the rock sample macroscopic fracture has occurred, but there is still a certain carrying capacity, a few rock infinitesimal continue FAILURE, the damage evolution magnitude gradually slows, the evolution of the slope of the curve gradually decreases and tends to 1. Rate to be Bijia He revealed: In the same confining pressure, sample damage development under Unloading under conditions much faster; ② same confining pressure, the rate of development of the specimen damage with unloading charge rate increases increase; ③ specimen strength only with the rate of damage evolution has been destroyed, and with each sample destroyed independent of how much of the total number of rock infinitesimal; And reasonable explanation based on the type of analysis of achievements, the development and distribution of deep cracks and deformation and failure characteristics.

Related Dissertations

  1. Copper River District Mouding Haojiatai Geochemical Prospecting Research,P618.41
  2. Yangbi prone to geological disasters zoning and Countermeasures Research,P694
  3. Meso-numerical Study on Elastic Brittle Rock Damage Evolution and Engineering Aapplications,TU452
  4. Research of the Effect of Interface on the Mechanical Properties of Unidirectional Fiber Reinforced Composites,TB332
  5. Experimental Study on Stress - Related Dynamic Damage Evolution of Concrete,TU528.0
  6. The Mechanism of Damage Evolution and the Model of Internal Expansion Force of Concrete under Sulfate Attack,TU528.0
  7. Experimental Study on Creep Characteristics of Deep Surrounding-Rock,TU452
  8. Stability of underground engineering based on the energy release rate,TU452
  9. Study on Acoustic Emission Mutation Characteristics and Prediction of Rock Unstable Failure under Triaxial Compression,TU458
  10. Research on Creating DEM of Suburban Roads Based on Large Scale Digital Map,P208
  11. Study on Loess Structural Evolution Mechanism of Shear Breakage Test,TU411.7
  12. Analysis of Stress Field in Rock Masses under Complicated Geological Condition,TV221.2
  13. The Mechanical Properties of Viscoelastic Materials with Inclusions Considering the Surface/Interface Effect,TB301
  14. Dynamic Response and Impact Fatigue of Cement Mortar under Confining Pressure,TU578.1
  15. Study on Geological Hazards Risk Zoning Base on GIS and Logistic,P208
  16. Hydropower station based on the causes of deep cracks J110 block stability evaluation,TV221.2
  17. Acoustic Emission Characteristics of FRP Composite Material Damage,TB302.5
  18. Creep Behaviors of Low-temperature Sintered Nanoscale Silver Paste at Elevated Temperatures,TG42
  19. Preparation of Reactive Powder Concrete and Research on Impact Behavior,TU528
  20. Research on Impact Behavior of Basalt Fiber Reinforced Concrete,TU528.572
  21. Study on Statistic Damge Constitutive Model of Concrete Based on Fractal Theory,TU528

CLC: > Industrial Technology > Building Science > Soil mechanics,foundation engineering > Rock ( rock ) mechanics and rock testing > Indoor rock test > Test the mechanical properties
© 2012 www.DissertationTopic.Net  Mobile