This study presents a comparative analysis of the deformation control effect of the hydraulic servo steel struts and ordinary steel struts of a foundation pit based on the measured axial force of the steel struts, lateral wall deflection, and ground surface settlement due to pit excavation. The results indicate that ordinary steel struts installed via axial preloading exhibit a disadvantageous axial force loss with a maximum value equal to 86.7% of the axial preloading force. When compared with ordinary steel struts, the hydraulic servo steel strut exhibits a superior supporting effect. The hydraulic servo steel strut adjusts the axial force in real time based on the deformation of the retaining structure and the axial force of the struts. Thus, the ratio of maximum lateral deflection to the excavation depth of a deep foundation pit in soft soil is less than 0.3%. Concrete struts undergo unsupported exposure during the excavation process, leading to sharply increasing deformation of the retaining structure. Therefore, regarding a foundation pit with strict requirements for deformation control, the use of hydraulic servo steel struts rather than concrete struts is recommended.

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Abstract. In recent years the highway develops rapidly in China, by the end of 2014, the total mileage of China's highway has reached 4.3 million kilometers. Among those, the total mileages of the speedway broke through the bottleneck of 110 thousand kilometers -which ranks the first in the world. With the fast development of basic traffic construction, the problem of safety has become more and more significant. However, some highway (especially, the long longitudinal gradient in the mountain area) has the high accident rate, which caused serious casualties and a great loss of social economy. Aim to this condition, the roads with high accident rate were investigated and analyzed in this paper and the reasons caused accident were studied. The research shows that, besides the carelessness of drivers and the deficiency of the vehicles, the phenomenon of continuous long down design was the same character among those mountain roads .Although those design were not beyond the limiting value, but the maximum longitudinal slope length and slope values almost reach the specification limit frequently, so the rationality of the road design regulations on continuous long down in the mountain road is also worthy of consideration. In this paper, based on the project case of the highway from Shizhong to HeXi in FuJian province, the operational safety of this road was estimated based on the security analysis method of USA, the study shows that, the highway's parameter on the longitudinal gradient is in accordance with Chinese design regulations, but according to the, the danger coefficient is very high in this section of accident highway, which dues to frequently traffic accident. In conclusion, the design regulations of the highway should be improved gradually to assure the traffic safety of highway.

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