Multiscale Laboratory Study and Numerical Analysis of Water‐Weakening Effect on Shale

Naturally fractured rock mass is susceptible to stress disturbance and could result in the stimulation of natural fractures and even serious geological hazards. In this work, multilevel uniaxial fatigue loading experiments were carried out to reveal the fracture and energy evolution of naturally fractured granite using stress-strain descriptions and energy evolution analysis. Results reveal the influence of natural fracture on mechanical properties of granite, regarding the fatigue lifetime, fatigue deformation characteristics, fatigue damage, energy evolution, and fatigue failure pattern. Volumetric and shear processes caused by the sliding and shearing along the natural fracture control the whole failure process. The energy dissipation and release characteristics are strongly impacted by natural fractures. The elastic energy and dissipated energy both decrease with increasing natural fracture volume, growth of the dissipated energy becomes faster for rock near to failure. It is proved that the dissipated energy is mainly used to activate the preexisting natural fractures.

Section: Discussionmentioning

confidence: 99%

Dynamic Fracture and Energy Evolution Characterization of Naturally Fractured Granite Subjected to Multilevel Cyclic Loads

Guo

Wang

2021

“…According to the filtration performance results of the siltgrade sieve, the filtration rate of the designed method for reinjection of geothermal tail water can reach 84.1%, 94.9%, and 82.1% when the particle sizes are 0.05~0.07, 0.07~0.09, and 0.09~0.10, and the sieve filtration rate is always the Methods of this paper Literature [3] Literature [4] Literature [2] 0.05-0.07 0.07-0.09 0.09-0.10 2 1 3 4 2 1 3 4 2 1 3 4 Grain size (mm) Figure 3: Testing result of fine-grained sieve filter performance. 6 Geofluids highest among the results of the several experimental methods tested, which means that this method can filter out the silt-grade sieve effectively.…”

Section: Geofluidsmentioning

confidence: 90%

“…Methods of this paper Literature [3] Literature [4] Literature [2] Figure 5: Experimental results on coarse-grade sieve filter performance. 7 Geofluids increased.…”

Section: Geofluidsmentioning

confidence: 99%

“…In China, the exploration of geothermal resources, which can effectively alleviate environmental pollution and energy shortages, has mainly concentrated on moderately deep sandstone reservoirs (the buried depth is 200 m-3000 m) [1,2]. However, in the exploration of geothermal resources in moderately deep sandstone reservoirs, challenges such as the gradual expansion of the geothermal descending funnel area arise, and the overexploitation of moderately deep sandstone in some areas brings about a series of problems such as the forced change in the geothermal environment, increased costs of heat transfer, imbalance of the hydrological budget, and decline of the dynamic water level [3][4][5].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Study on Optimization of Geothermal Tail Water Reinjection Process in Moderately Deep Sandstone

Wang

Liu

et al. 2021

The existing test methods of geothermal tail water reinjection effect in sandstone geothermal reservoirs are not suitable for moderately deep and deep sandstone geothermal reservoirs, resulting in the poor filtration performance of fine-grained reservoirs. Therefore, a test method for the geothermal tail water reinjection effect in a moderately deep sandstone geothermal reservoir is proposed. This paper studies the static compatibility of raw water and geothermal tail water under different mixing ratios, determines the indexes affecting the reinjection effect of moderately deep sandstone geothermal reservoir tail water, analyzes the weight set of each influencing factor, and formulates a test standard for the reinjection effect of geothermal reservoir tail water. Finally, a tracer is selected to trace the reinjected tail water in the geothermal reservoir, and the tracer is used to obtain the result of each previously determined index. Eventually, the final reinjection effect of the geothermal tail water is obtained. The experimental results show that the fine-grade filtration performance, silt-grade filtration performance, and coarse-grade filtration performance of this method are improved compared with those of other methods; thus, the particle filtration performance is better, and the reinjection effect of geothermal reservoir tail water is better, which has a great significance for the geothermal resource exploitation of moderately deep sandstone.

“…Plastic reinforced soil embankments are widely used in engineering practice. Although scientific and technological researchers have carried out certain research work on the seismic effects of reinforced soil slopes, the seismic effects of plastic geogrid-reinforced embankments have rarely been investigated [20][21][22][23][24][25]. The current seismic design of highways nor does the code evaluate the seismic performance of plastic-reinforced embankments.…”

Section: Introductionmentioning

confidence: 99%

Model Test Study on Dynamic Response of Expressway Plastic-Reinforced Earth Embankment under Earthquake

Han

et al. 2021

Aiming at the seismic response of plastic geogrid-reinforced embankments, with Zhounan Expressway as the research engineering background, a self-designed seismic-rainfall coupled slope model test system was designed and used to produce 1 : 20 scale plastic geogrid-reinforced embankments. Moreover, the physical model of the unreinforced embankment under Hanshin wave, Wenchuan wave, Tianjin wave, etc. was also studied to carry out comparative analysis on seismic response and dynamic response on test model. The dynamic characteristics and dynamic response of the embankment model were tested from low to high seismic intensity; the changes of the embankment’s natural frequency, damping ratio, acceleration at the measuring point, and dynamic earth pressure were analyzed; and the main influencing factors and damage to the embankment seismic response feature were discussed herein. The test results showed that the initial natural frequency of the reinforced embankment was 42.4% higher than that of the unreinforced embankment, and its initial damping ratio reduced by 19.4%. The attenuation effect of the natural frequency and damping ratio of the reinforced embankment with the loading history was significantly lower than that of the unreinforced embankment. Embankment reinforcement exhibited a very good inhibitory effect on the PGA amplification effect of the embankment, and the inhibitory effect on the interior of the slope was more significant than that on the slope. Moreover, the type of seismic wave, the amplitude of the seismic wave, and the frequency of the seismic wave significantly influenced the PGA amplification effect of the embankment. The peak dynamic soil pressure of the unreinforced embankment at the same location was significantly greater than that of the reinforced embankment. The two embankment models showed significantly different antivibration damage performance. After the peak acceleration of 2 m s-2 was loaded, no cracks were seen on the surface of the embankment model. When the peak acceleration of 3 m s-2 was loaded, on the slopes of the two embankment models, smaller cracks were observed in the middle and upper parts of the face. When the peak acceleration of 4 m s-2 was loaded, the failure of the unreinforced embankment model was obvious. Large cracks on the top of the slope could reach 16 mm in width, and 27 mm settlement appeared at the top, and the slope was convex. The reinforced embankment model was only on the slope shoulder. Moreover, there were fine cracks on the top, and the slope top settlement was less than 5 mm. The research results provide theoretical support for preventing and controlling the road embankment vibration diseases and improving highway durability design.