Expansion project of 1.3 Million t/a coal coking plant of Guizhou Qiangui Tianneng Coal Coking Co., Ltd.
Supporting technology for backfilling works on high slope
1. Introduction
The terrain of China is of the three-level terrace and fluctuates greatly. The mountainous area accounts for about 70% of the national land area. Limited by the existing conditions of resources and energy structure in China, a large number of major construction projects such as coal power, coal chemical industry and coal mines are built in the mountainous areas. Constrained by mountainous terrain and production technology, the geological disaster problem of "high filling and deep excavation" in the proposed construction site is outstanding. In engineering construction, it is necessary to build a vertical slope with high embankment to provide a construction site for major construction projects, so as to keep the safety of engineering construction and operation.
The Expansion Project of Coal Coking Plant of Guizhou Qiangui Tianneng Coal Coking Co., Ltd. is a large-scale coal chemical project with a total investment of about RMB 3.5 billion. The stability of filling slope (31m) and supporting structure of platform 1541 built in the project site is the key to the whole project construction and work safety.
Figure 1 Site of the project area Figure 2 Slope of the vertical retaining wall
2. Treatment solution
By means of engineering geological mapping, drilling and testing, and indoor simulation, the mechanical mechanism of soil-rock mixture and typical loess filler wass revealed. In view of the narrow space of engineering site in mountainous area and the lack of slope setting conditions, the supporting technology system of high-embankment vertical slope engineering in mountain area was established. The multi-dimensional (field) online monitoring system was constructed, and a new method for predicting post-construction settlement of fill area was established.
Figure 3 Solutions
Figure 4 Framework of the online monitoring system | Figure 5 Profile of support structure and sensor arrangement |
3. Construction situation
36 groups of indoor simulation tests were carried out, two numerical calculation models of supporting structures were established, two sections are monitored, 190 sensors of various types are buried, two sets of wireless remote acquisition devices and one wireless transmission system are established, and online monitoring of key indicators such as stress, temperature and earth pressure is realized.
(a) Equipment (b) Sample preparation (c) Sample loading
Figure 6 Laboratory simulation test of backfill
Figure 7 Calculation model for numerical simulation
(a) Earth Pressure installation drawing | (b) Stress meter installation | (c) Acquisition system |
Figure 8 Slope monitoring system
4. Achieved Accomplishment
By means of large-scale triaxial shear test, it is found out that "volume deformation-radial strain curve" of soil-rock mixed filler is parabolic, which modifies Duncan-Chang constitutive model and provides theoretical basis for load calculation of supporting structure.
Figure 9 Duncan-Chang model of mixed filler (revised)
On-line real-time monitoring of earth pressure, stress and temperature field has achieved a good effect.
Figure 8 Variation subject to on-site monitoring of pressure at the base of front retaining wall with time
Figure 10 Variation subject to on-site monitoring of the internal temperature of the front retaining wall with time
Figure 11 Cumulative variation process curve of height difference (h) at the bottom settlement monitoring point of the front retaining wall on the slope
The modified "FDA method" and "micro-element method" suitable for settlement observation in high-embankment areas were established, and the temporal and spatial evolution law of post-construction settlement in high-embankment areas was predicted. The block of "creep generalized layer" of filling body was constructed, and the inversion prediction method of post-construction settlement of high embankment based on FEM numerical calculation and layered iteration was put forward.
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