Excavations may cause excessive ground movements, resulting in potential damage to laterally adjacent tunnels. The aim of this investigation is to present a simple assessment technique using a multivariate adaptive regression splines (MARS) model, which can map the nonlinear interactions between the influencing factors and the maximum horizontal deformation of tunnels. A high-quality case history in Tianjin, China, is presented to illustrate the effect of excavation on the tunnel deformation and to validate the FEM. The hypothetical data produced by the FEM provide a basis for developing the proposed MARS model. Based on the proposed model, the independent and coupled effects of the input variables (i.e. the normalized buried depth of tunnels Ht/He, the normalized horizontal distance between tunnels and retaining structures Lt/He, and the maximum horizontal displacement of retaining structures, δRmax) on the tunnel response are analysed. The prediction precision and accuracy of the MARS model are validated via the artificial data and the collected case histories.
Maternal eff ects are one of the most interesting topics in evolutionary ecology as they can aff ect the rate of evolution and population dynamics by phenotypic manipulation of off spring related to fi tness. At present, studies examining the interaction between maternal environment eff ects and maternal age (birth order) eff ects are scarce. We designed an experiment to reveal whether environmentally induced maternal manipulation works equally on off spring across birth orders in rotifer Brachionus calycifl orus. In the experiment, newborn amictic mothers (F0) were cultured parallelly in low (LD) and high (HD) population density. Off spring (F1) of young (YF0) and old (OF0) mothers in both LD and HD groups were cultured under a crowded condition and the mixis ratios of both F1 and F2 were examined. Results show that F1 from HD-YF0 had a signifi cantly higher mixis ratio and those amictic ones produced daughters (F2 ) with higher mixis ratio in response to crowding than those from HD-OF0. In contrast, no such diff erences among F1 siblings were found in the LD-F0 group. Therefore, the eff ect of maternal age on the sexual propensity of the off spring can be aff ected independently by the maternal population density. 相似文献