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为揭示某软岩硐室的合理支护时间,结合调压井硐室的结构特征,建立三维有限元模型,基于幂律流变模型,研究了无支护(方案1)、及时支护(方案2)、滞后15d支护(方案3)、滞后30d支护(方案4)四种方案下施工期及完建150d内衬砌的位移、应力和围岩塑性区开展范围。结果表明,方案3衬砌的应力水平和位移较其他2种支护方案小,最大压应力约为方案2的64%、方案4的70%;最大位移约为方案2的2倍、方案4的1.5倍;支护越及时,围岩的塑性区开展范围就越小,但方案3围岩最大塑性区范围为8.5m,与方案2的围岩塑性区相差较小,且塑性区发育深度小于围岩锚固深度,从充分发挥围压自承能力和支护结构的安全性角度综合分析,建议采用方案3。研究结果为此类工程设计提供借鉴。
In order to reveal the reasonable supporting time of a soft rock chamber and to combine with the structural characteristics of the surge chamber, a three-dimensional finite element model was established. Based on the power-law rheological model, the effects of unsupported (Scheme 1) and timely support Plan 2), lag 15d support (Scheme 3), lagging 30d support (Scheme 4) under the construction of four programs and completion of 150d lining within the displacement, stress and plastic zone surrounding rock development range. The results show that the stress level and displacement of the lining of Scheme 3 are smaller than those of the other two schemes. The maximum compressive stress is about 64% of that of Scheme 2 and 70% of that of Scheme 4. The maximum displacement is about twice of that of Scheme 2, 1.5 times; the more timely the support is, the smaller the plastic zone of surrounding rock is developed, but the maximum plastic zone of surrounding rock of scheme 3 is 8.5m, which is smaller than the plastic zone of the surrounding rock of scheme 2, and the depth of plastic zone is less than Surrounding rock anchoring depth, from full exert confining pressure self-supporting capacity and supporting structure of the safety point of view of comprehensive analysis, it is recommended to use Option 3. The research results provide reference for such engineering design.