2种锚杆耦合支护的喷混凝土力学模型

Mechanical models of wet shotcrete with two kinds of bolt coupling support

为确定混凝土层受破坏时中性层的位置并探究不同支护方式下锚喷支护参数与围岩自承能力间的关系,以弹性力学理论为手段,分别将湿喷+管缝式锚杆与湿喷+树脂锚杆耦合支护视为简支梁与固支梁模型,得出这2种耦合支护模型的数学解析式;用数值方法得出混凝土层受破坏时中性层偏离质心的位移计算公式;结合莫尔-库仑准则得出巷道围岩自承能力与锚杆间距、混凝土喷层厚度及混凝土强度之间的力学模型;推导得出喷层厚度每增加10 mm,湿喷+管缝式锚杆与湿喷+树脂锚杆模型中岩体自承能力最高分别提高0.01 MPa与0.40 MPa,喷射混凝土的抗拉强度与围岩破坏所需最大主应力间大致呈线性关系,进而为合理优化巷道支护参数提供依据。

In order to determine the position of the neutral layer when the concrete layer is in failure, and explore the relationship between parameters of bolt-shotcrete support and surrounding rock self-supporting capacity under different ways of support, the mathematic analysis of this two coupling support models was obtained by means of elastic mechanics theory, with wet shotcrete pluses slotted tube bolt and resin bolt being regarded as beam and fixed-end beam, respectively. The neutral layer displacement formula of deviating from the center of mass were obtained by using numerical method. Combined with Mohr？coulomb criterion, the mechanical model of the bolt spacing, the shotcrete layer thickness and strength to surrounding rock self-supporting capacity was obtained. The results show that surrounding rock self-supporting capacity increases up to 0.01 MPa and 0.40 MPa in resin wet shotcrete pluses slotted tube bolt and resin bolt respectively when shotcrete layer thickness increases every 10 mm, and there is approximately linear relationship between tensile strength of shotcrete and the desired maximum principal stress of rock damage, which provides basis for the reasonable roadway supporting parameters optimization.