水库诱生的孔压变化及应力特征

THE PORE PRESSURE VARIATION AND STRESS CHARACTERISTICS INDUCED BY RESERVOIR

应用“固结问题和布辛涅斯克问题解”,计算了丹江水库水位在130m和157m两种情况下,库区基岩体深度分别为1、3、5、7、9、11、13和15km时的水压应力场、变形场和超孔隙水压力场。结果表明,σ_1、σ_3和τ_(max)在库中心位置最大,库岸边较小;同时σ_1和σ_3在库中心均显压性,而在库岸边σ_3显张性;垂直位移在库中心最大(7cm),而水平位移在库岸边最大(0.5cm);超孔隙水压力一般在库中心深水区库基下3—9km处最大,库岸边和浅水区较小;体应变一般在库中心位置形成压缩区,而在库岸边则形成拉伸应变区并同时向四周扩展,与诱发地震震中分布相一致。

Using the theory of consolidation and Boussinesq solution, the additional stress field, displacement field and over-pore-pressure field are calculated under the water-loadings for Danjiang Reservoir. The water levels are assumed to be 130m and 157m and the depth of bedrock body from reservoir bottom is 1, 3, 5, 7, 9, 11, 13 and 15 km respectively. The results show that: (1) the maximum values of O_1, O_3,τ_(max) appear at the centre of reservoir and the smaller values of O_1,O_3, τ_(max), appear at the reservoir bank; (2) both O_1 and O_3 at the centre of reservoir are compressive and O_3 near bank is tensile; (3) the maximum vertical displacement (7cm) occurs at the middle of reservoir and the maximum horizontal displacement (0.6cm) at the bank; (4) the maximum over-pore-pressure generally appears at the deepwater region of reservoir from 3km to 9km below the reservoir bottom; (5)the volume strain forms a compressive region at the centre area of reservoir, and a tensile at the bank area and expands in all directions being consistent with the distribution of epicenter of induced earthquake.