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Reverse fault movement is one of the threats for the structural integrity of buried oil-gas pipelines caused by earthquakes. Buckling behavior of the buried pipeline was investigated by finite element method. Effects of fault displacement, internal pressure, diameter-thick ratio, buried depth and friction coefficient on buckling behavior of the buried steel pipeline were discussed. The results show that internal pressure is the most important factor that affecting the pipeline buckling pattern. Buckling mode of non-pressure pipeline is collapse under reverse fault. Wrinkles appear on buried pressure pipeline when the internal pressure is more than 0.4 Pmax. Four buckling locations appear on the buried pressure pipeline under bigger fault displacement. There is only one wrinkle on the three locations of the pipeline in the rising formation, but more wrinkles on the fourth location. Number of the wrinkle ridges and length of the wavy buckling increase with the increasing of friction coefficient. Number of buckling location decreases gradually with the decreasing of diameter-thick ratio. A protective device of buried pipeline was designed for preventing pipeline damage crossing fault area for its simple structure and convenient installation. Those results can be used to safety evaluation, maintenance and protection of buried pipelines crossing fault area.

This paper addresses the mechanical behavior of buried steel pipeline crossing subsidence strata. The investigation is based on numerical simulation of the nonlinear response of the pipeline-soil system through finite element method, considering large strain and displacement, inelastic material behavior of buried pipeline and the surrounding soil, as well as contact and friction on the pipeline-soil interface. Effects of key parameters on the mechanical behavior of buried pipeline were investigated, such as strata subsidence, diameter-thickness ratio, buried depth, internal pressure, friction coefficient and soil properties. The results show that the maximum strain appears on the outer transition subsidence section of the pipeline, and its cross section is concave shaped. With the increasing of strata subsidence and diameter-thickness ratio, the out of roundness, longitudinal strain and equivalent plastic strain increase gradually. With the buried depth increasing, the deflection, out of roundness and strain of the pipeline decrease. Internal pressure and friction coefficient have little effect on the deflection of buried pipeline. Out of roundness is reduced and the strain is increased gradually with the increasing of internal pressure. The physical properties of soil have a great influence on the mechanical properties of buried pipeline. The results from the present study can be used for the development of optimization design and preventive maintenance for buried steel pipelines.

Purpose: The purpose of this study is to determine whether a dose-response relationship in stereotactic body radiotherapy (SBRT) for hepatocellular carcinoma (HCC) is observed and to identify whether local control or response affects survival outcome. Methods: Between March 2003 and February 2011, 108 patients with 122 lesions were treated with SBRT for HCC. The indications for SBRT were unsuitable for surgery or other ablative therapies and incomplete response of transarterial chemoembolization (TACE). The inclusion criteria of this study are SBRT using 3 fractions and longest diameter ≤ 7.0 cm. Eighty-two patients with 95 lesions were analyzed. Median age was 60 years (range, 39-79 years). Seventy-four patients (90%) had Child-Pugh class A and 8 patients had B7. All patients had one or more TACE and the median number of TACE sessions per patient was 2 (range, 1-14). The median longest diameter was 3.0 cm (range, 1.0-7.0 cm). The median SBRT dose was 51 Gy (range, 33-60 Gy). Results: The median follow-up duration for all analyzed patients was 30 months (range, 4-81 months). Local control and overall survival rates at 2 years after SBRT were 87% and 63%, respectively. The 2-year local control rates for lesions treated with SBRT doses of >54 Gy, 45-54 Gy, and <45 Gy were 100%, 78%, and 64%, respectively (p=0.0087). In multivariate analysis, SBRT dose and age were significant prognostic factors for local control. The 2-year overall survival rates for patients with and without local failure were 27% and 68%, respectively (p=0.0001). In multivariate analysis, SBRT dose and Barcelona Clinic Liver Cancer stage were significant prognostic factors for overall survival. Five patients (6%) experienced grade 3 or higher gastrointestinal toxicity. The estimated SBRT dose to achieve 90% LC at 2 years is 54 Gy in 3 fractions. In selected patients with SBRT dose > 54 Gy and longest diameter ≤ 5.0 cm, the treatment outcomes of SBRT were comparable with those of radiofrequency ablation (RFA). Conclusions: The present study strongly suggests a dose-response relationship in SBRT for HCC. Excellent local control rates are achieved with SBRT dose of more than 54 Gy or greater. Higher local control rates resulted from increasing dose may be survival benefit for inoperable HCC. We suggest SBRT dose of more than 54 Gy, if normal tissue constraints allow. In the patients with small-sized HCC, high-dose SBRT may be as effective and safe treatment modality as RFA. Disclosure: No significant relationships. [ABSTRACT FROM AUTHOR]