基于增量法钢板桩围堰的安全性计算方法

分析了现有的钢板桩计算理论, 计算了钢板桩围堰的土压力、静水压力、流水压力、波浪力与支撑力; 分析了钢板桩围堰的施工工序, 将钢板桩视为非线性弹性地基梁, 建立了基于增量法的非线性弹性地基梁挠曲微分方程, 计算了地基土水平抗力系数、钢板桩弯曲变形系数与内外荷载增量, 研究了钢板桩围堰各工况下受力与变形; 基于裕溪河大桥桥墩基础的钢板桩围堰, 验算了钢板桩围堰的内力、变形、强度、整体稳定性、抗倾覆安全性与抗隆起安全性。计算结果表明: 钢板桩最大位移为38.12 mm, 小于规范值80 mm; 钢板桩最大许用应力为168.60 MPa, 小于规范值218.52 MPa; 管桩最大许用应力为112.29 MPa, 小于规范值174.07 MPa; 钢板桩围堰整体稳定安全系数为2.8, 大于规范值1.3;4种工况下抗倾覆安全系数分别为3.4、2.8、2.9、1.9, 大于规范值1.2;根据普朗德尔理论与太沙基理论计算的抗隆起安全系数分别为3.1和3.5, 大于规范值1.6。可见, 基于增量法钢板桩围堰的安全性计算结果满足相关规范要求, 计算方法合理、可靠。

Security calculation method of steel sheet pile cofferdam based on incremental method

The existing calculation theories of steel sheet pile were analyzed, and the soil pressure hydrostatic pressure, flowing water pressure, wave pressure and supporting pressure acting on steel sheet pile cofferdam were calculated.The construction process of steel sheet pile cofferdam was analyzed, the steel sheet pile was taken as nonlinear elastic foundation beam, the nonlinear differential equations of elastic foundation beam were established based on the incremental method, the horizontal resistance coefficient of foundation soil, the bending deformation coefficient of steel sheet pile and the increments of internal and external loads of steel sheet pile cofferdam were calculated, and the forces and deformations of steel sheet pile under all conditions were studied.Based on the steel sheet pile cofferdam of Yuxi River Bridge, the internal force, deformation, strength, overall stability, anti-overturning safety, anti-uplift safety of steel sheet pile cofferdam were checked.Calculation result shows that the maximum displacement is 38.12 mm and less than the specification value of 80mm; the maximum allowable stress of steel sheet pile is 168.60 MPa and less than the specification value of 218.52MPa; the maximum allowable stress of pipe pile is112.29 MPa and less than the specification value of 174.07 MPa; the overall stability safety factor of steel sheet pile cofferdam is 2.8and greater than the specification value of 1.3;the antioverturning safety factors under 4cases are 3.4, 2.8, 2.9, 1.9respectively and greater than the specification value of 1.2;the anti-uplift safety coefficients based on Prandtl theory and Terzaghi theory are 3.1, 3.5respectively and greater than the specification value of 1.6.Obviously, the safety calculation results of steel sheet pile cofferdam based on the incremental method meet the requirements of the relevant specification, so the calculation method is reasonable and reliable.