覆土偏载对浅埋主平硐衬砌支护结构影响研究

Study on the influence of the static load of the surface covering soil on the stability of the shallowburied main adit

为研究载荷对主平硐支护结构稳定性的影响规律,以某矿浅埋料石衬砌支护的主平硐为工程背景,综合采用理论分析、数值模拟和现场观测相结合的研究方法,分析支护结构稳定性影响因素,研究覆土静载作用下支护结构弯矩和轴力以及位移和最大主应力分布特征,并从料石衬砌结构中各砌块稳定性的角度分析支护结构的整体稳定性。研究结果表明:埋深和外部载荷扰动是影响支护结构稳定性的主要因素。覆土静载作用下支护结构弯矩和轴力呈非对称分布,其中弯矩最大值位于非填土侧,轴力最大值位于填土侧,且支护结构中部位置内表面将产生拉破坏,但该位置对应外表面的压应力远小于其抗压强度,使得内表面即使产生裂纹,也将因外表面砌块相互挤压而处于稳定状态,现场通过在裂隙表面涂抹素混凝土也验证了理论分析结果;并确定了随着埋深增大,支护结构受覆土静载的影响减小。数值模拟确定覆土静载使得支护结构最大位移和拉应力区域偏向填土侧,与理论分析结果吻合。同时以砌块结构竖直方向合力和砌块与砂浆间的相互作用力为指标,确定砌块结构处于稳定状态。该研究可为类似条件下料石衬砌支护结构的稳定性分析提供借鉴和参考。

In order to study the influence of load on the stability of the main adit support structure,this paper takes the main adit of shallow buried rock lining support in a mine as the engineering background,and adopts the comprehensive research method of theoretical analysis,numerical simulation and field observation,analyzes the factors affecting the stability of the supporting structure,and studies the bending moment,axial force,displacement and maximum principal stress distribution characteristics of the supporting structure under the static load of the covering soil.The results show that the buried depth and external load disturbance are the main factors affecting the stability of the support structure.The bending moment and axial force of the supporting structure are distributed asymmetrically under the static load of the covering soil,in which the maximum bending moment is located on the non-filling side,and the maximum axial force is located on the filling side,and the inner surface of the supporting structure will have tensile failure in the middle position.However,because the compressive stress of the outer surface corresponding to this position is much smaller than its compressive strength,even if the inner surface cracks,it will be in a stable state due to the mutual extrusion of the outer surface blocks. The theoreticalanalysis results are obtained;and it is determined that with the increase of burial depth,the influence ofthe support structure by the static load of the covering soil decreases. Numerical simulations confirm thatthe static load of the overburden makes the maximum displacement and tensile stress area of the supportingstructure deviate to the filling side,which is consistent with the theoretical analysis results. At thesame time,the resultant force in the vertical direction of the block structure and the interaction force betweenthe block and the mortar are used as indicators to determine whether the block structure is in a stablestate. This study can provide a reference for the stability analysis of stone-lined support structures undersimilar conditions.