Braced Excavations: Temperature, Elastic Modulus, and Strut Loads

A new empirical approach to estimate temperature effects on strut loads in braced excavation

“…Output results and prepare the input parameters for level n-1 strut. Finally, the equilibrium among soil, retaining wall, and strut is achieved, which are unfortunately not involved in the papers ( Endo and Kawasaki ,1963;Chapman et al, 1972;Boone and Crawford, 2000;Gaba et al, 2003)and presented graphically in Figures 7-9. In addition, after the temperature-induced strut load and the corresponding displacement Yn of the n-th-level strut was obtained, (see Fig.…”

“…In last decades , many researchers and practitioners have documented a significant amount of cases in related to temperature effects on strut loads (Chapman et al, 1972;Twine and Roscoe, 1997;Kumagai et al, 1999;Richards et al, 1999;Boone and Crawford, 2000;Hashash et al, 2003;Osborne et al, 2007;Chambers et al, 2016). By analyzing monitoring datum offered by above literatures, the changes of thermal loads in struts vary from approximately 65kN to 19kN per 1 °C as to different retained soil and various types of retaining structures across almost the world.…”

“…Nevertheless, as to a majority of engineers and practioners, empircal approaches are still more convinient in certain occasion. Thus, mainly three kinds of approaches ( Endo and Kawasaki ,1963;Chapman et al, 1972;Twine and Roscoe, 1997;Boone and Crawford, 2000) were proposed to calcaulted temprature-induced loads in struts. (i) Endo and Kawasaki (1963)[as citied in (Boone and Crawford, 2000)] studied the relationships between thermal load and the elastic properties of the retained soil and proposed an equation by taking the retained soil as springs.…”

“…However, the equation does not take the effect of strut spacing into account. (ii) By considering the lateral deformation of large sections of the retaining wall analogous to elastic settlement of a rectangular foundation and then using the Boussinesq solution (Terzaghi et al, 1996), an empirical expression ( Chapman et al, 1972) was derived and later employed to estimate the thermal loads in several reported cases (Hashash et al, 2003;Boone and Crawford, 2000). (iii) Furthermore, Twine and Roscoe(1997) and Gaba et al (2003) suggested that temperature-induced loads can be estimated by the emprical expression, consisting of the degree of end restraint provided by the wall and the retainded soil and the thermal loads ocurred in strut with tow ends fixed.…”

Studies on Construction Pre-control of a Connection Aisle Between Two Neighbouring Tunnels in Shanghai by Means of 3D FEM, Neural Networks and Fuzzy Logic

“…Neaupane et al (1999) (Neaupane and Yamabe 2001;Neaupane and Achet 2004;Neaupane and Adhikari 2006) have put forward a coupled thermo-hydro-mechanical nonlinear model for the frozen medium and applied back-propagation neural networks and multi-layered perception to the tunneling-induced ground movement and landslide monitoring. Boone and Crawford (2000) have studied the relationships between strut loads, earth pressure, temperature and the measurements provided by strain gauges for a braced excavation project and developed a new approach for separation of earth-induced and temperatureinduced loads. Master et al (2000) have coupled temperature to a double-porosity model of deformable porous media.…”