土压平衡盾构楔犁刀松动砂卵石地层力学行为研究

为研究砂卵石地层中土压平衡盾构刀土相互作用的力学行为，揭示楔犁刀的楔犁松动机制，首先，将刀盘前方砂卵石地层等效为连续介质，采用Terzaghi地基承载力模型与Mckyes-Ali模型求解楔犁刀楔犁松动作用下砂卵石地层的破坏强度； 然后，引入楔犁指数k表征楔犁刀反复松动地层、地层颗粒间咬合作用被逐渐破坏、地层强度逐渐降低的楔犁松动状态，分析复杂刀具配置条件下整盘刀具楔犁地层时的受力情况； 最后，通过计算得到单把楔犁刀楔犁地层所需的环向松动力及轴向顶进力，并提出砂卵石地层楔犁刀梯次松动地层与刮刀剥落渣土的受力计算方法，得到整盘刀具松动地层所需的扭矩及贯入推力，分析贯入推力和扭矩的影响因素。采用本文提出的计算分析方法计算土压平衡盾构楔犁刀与刮刀组合松动砂卵石地层时刀具的受力（推力和扭矩）与工程实测结果基本相符。研究结果表明： 楔犁刀分层、超前于刮刀布置可以有效降低松动地层所需的贯入推力和扭矩，达到降低盾构掘进所需总推力及总扭矩的目的。

Mechanical Behavior of Sandy Gravel Strata Cut byWedge-Shaped Cutter on Earth Pressure Balance Shield

To investigate the mechanical behavior of the interaction between cutters on an earth pressure balance shield and the sandy gravel strata as well as reveal the loosening mechanism of wedge shaped cutters, the sandy gravel strata ahead of the cutterhead are regarded as a continuous medium, and the failure strength of the strata under loosening effect of a wedge shaped cutter is determined using the Terzaghi bearing capacity formula and Mckyes Ali model. Then, the plow loosening index WT《TNR#I》]kWT《TNR》] is introduced to characterize the principle of plow loosening when the wedge shaped cutter repeatedly cuts the strata, the friction and strength between particles are gradually reduced, and the stratum force under the cutterhead cutting has a complex cutter arrangement. The circumferential loosening force and axial jacking thrust required for strata cutting by a single wedge shaped cutter are calculated, stress calculation methods for loosening the wedge shaped cutter and dropping the scrape cutter are proposed, the torque and penetration thrust required by the cutterhead are obtained, and the influence factors of both thrust and torque are analyzed. The stress state(torque and thrust) of wedge shaped cutters and scrapers calculated using the proposed methods agree well with the monitoring results, demonstrating that the thrust and torque of the cutterhead required for strata cutting can effectively reduce the layered arrangement of wedge shaped cutters ahead of scrapers, thereby reducing the total thrust and total torque of the shield.