Base Instability Triggered by Hydraulic Uplift of Pit-in-Pit Braced Excavations in Soft Clay Overlying a Confined Aquifer

Fu-quan Chen,Guangji Miao,Fengwen Lai 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.6

The aim of this study is to investigate the coupling effects of re-excavation and hydraulic uplift on base instability of pit-in-pit (PIP) braced excavations. The numerical model of PIP braced excavation in Shanghai soft clay overlying a confined aquifer was established by upper-bound finite element limit analysis (UBFELA) method. The effects of the sensitive design parameters (i.e., the artesian pressure, thickness and undrained shear strength of the aquitard and excavation width of inner pit) on failure mechanisms and upper-bound safety factor (FS) against hydraulic uplift were analyzed. The results show that the value of FS increases with an increase in the thickness and undrained shear strength of the aquitard, but decreases with increasing the artesian pressure and excavation width of inner pit. The failure modes can be typically classified into three categories: circular slip surface in outer pit (M1), hydraulic uplift combined with circular slip surface in entire PIP system (M2), and basal hydraulic uplift in inner pit (M3); then the corresponding critical artesian pressure is determined. Finally, the average value of critical artesian pressure used to distinguish the three types of failure modes is recommended as the design value against hydraulic uplift in the PIP system, and validity is verified by the comparison with the current design methods. The proposed stability design by UBFELA contributes to ensure the serviceability and performance of PIP system.

[Poster Presentation] PREPERATION OF AMPHOTERIC STARCHS AND STUDY ON WET END CHEMISTRY IN PAPERMAKING

Chen Fu-Shan,Xie Lai-Su,Wang Hai-Yi,Long Yan-Quan Tianjin Universi 한국펄프·종이공학회 1999 한국펄프종이학회 기타 간행물 Vol.- No.-

Amphoteric polymers have brought to papermakers' attention gradually. In this paper, a series of amphoteric starches with different cationic and anionic degree of substitution (DS) are prepared. Better product has been selected and used under different condition.<br/> As retention and drainage aids, amphoteric starches were used in 'shorter fiber length, weak strength and poor drainage bleached AQ-Soda wheat straw pulp. In neutral and alkaline papermaking system, when amphoteric starches contain 0.024anionic degree of substitution (DS), it is shown that the higher the cationic degree of substitution (DS) in amphoteric starches, the better the filler retention. The filler retention is improved 12.5%. 30.3%, and 35.1 % and 32.5% respectively by adding 1 % amphoteric starch LS-L2 -I (0.034), LS-L2-2 (0.040). LS-L2-3 (0.047) and LS-L2-4 (0.052). But the strength of handsheets is affected a little. By adding 2% Al2 (S04) J and 1.5% LS-L2-3 at pH 7.5, filler retention can be improved from 38% to 80%. and breaking length of sheet only decreases 3.2%. As dry strengthening aids, amphoteric starches were used in eucalyptus APMP. Amphoteric starches are used in eucalyptus APMP. The amphoteric starch LS-L2-2 is better dry strength aid. Adding 1% LS-L2-2 can improve breaking length 24.5%. burst index 42.9%. tear index 38.8%. folding endurance and density of the handsheets.

Expression and Prognostic Role of MEKK3 and pERK in Patients with Renal Clear Cell Carcinoma

Chen, Qi,Lu, Hong-sheng,Gan, Mei-fu,Chen, Lan-xi,He, Kai,Fan, Guang-min,Cao, Xue-quan Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.6

Mitogen-activated protein kinase/extracellular signal-regulated kinase kinase kinase 3 (MEKK3) is an important serine/threonine protein kinase and a member of the MAPK family. MEKK3 can effectively activate the MEK/ERK signaling pathway and promote an autocrine growth loop critical for tumor genesis, cell proliferation, terminal differentiation, apoptosis and survival. To explore the relationship between MEKK3 and cell apoptosis, clinicopathology and prognosis, we characterize the expression of MEKK3, pERK and FoxP3 in the renal clear cell carcinoma (RCCC). Protein expression was detected by tissue microarray and immunochemistry in 46 cases of RCCC and 28 control cases. Expression levels of CD3+,CD3+CD4+,CD3+CD8+,CD4+CD25+, CD4+CD25+ FoxP3+ were assessed by flow cytometry and analyzed for their association with pathological factors, correlation and prognosis in RCCC. Expression of MEKK3, pERK and FoxP3 was significantly up-regulated in RCCC as compared to control levels (p<0.01), associated with pathological grade (p<0.05)and clinical stage (p<0.05). CD4+CD25+ Foxp3+ Treg cells were also significantly increased in RCCC patients (p<0.05). Cox multivariate regression analysis showed that MEKK3, pERK expression and patholigical stage were independent prognostic factors in patients with RCCC (p<0.05). MEKK3 can be used as an important marker of early diagnosis and prognostic evaluation in RCCC. It may be associated with imbalance of anti-tumor immunity and overexpression of pERK. Expression of MEKK3 and pERK are significantly increased in RCCC, with protein expression and clinical stage acting as independent prognostic factors.

MEKK3 and Survivin Expression in Cervical Cancer: Association with Clinicopathological Factors and Prognosis

Cao, Xue-Quan,Lu, Hong-Sheng,Zhang, Ling,Chen, Li-Li,Gan, Mei-Fu Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.13

Mitogen-activated protein kinase/extracellular signal-regulated kinase kinase kinase 3 (MEKK3) is an important protein kinase and a member of the MAPK family, which regulates cellular responses to environmental stress and serves as key integration points along the signal transduction cascade that not only link diverse extracellular stimuli to subsequent signaling molecules but also amplify the initiating signals to ultimately activate effector molecules and induce cell proliferation, differentiation and survival. To explore the relationship between MEKK3 and cell apoptosis, clinicopathology and prognosis, we characterize the expression of MEKK3 and survivin in cervical cancer. MEKK3 and survivin expression was measured by RT-PCR and Western blotting of fresh surgical resections from 30 cases of cervical cancer and 25 cases of chronic cervicitis. Protein expression was detected by tissue microarray and immunochemistry (En Vision) in 107 cases of cervical cancer, 86 cases of cervical intraepithelial neoplasia (CIN), and 35 cases of chronic cervicitis. Expression patterns were analyzed for their association with clinicopathological factors and prognosis in cervical cancer. Expression of MEKK3 and survivin mRNA was significantly higher in cervical cancer than in the controls (p<0.05). MEKK3 and survivin expression differed significantly between cervical carcinoma, CIN, and cervicitis (p<0.05) and correlated with clinical stage, infiltration depth, and lymph node metastasis (p<0.05). MEKK3 expression was positively correlated with survivin (p<0.05). Kaplan-Meier survival analysis showed that MEKK3 and survivin expression, lymph node metastasis, depth of invasion, and FIGO stage reduce cumulative survival. Cox multivariate regression analysis showed that MEKK3, survivin, and clinical staging are independent prognostic factors in cervical cancer (p<0.05). Expression of MEKK3 and survivin are significantly increased in cervical cancer, their overexpression participating in the occurrence and development of cervical cancer, with protein expression and clinical staging acting as independent prognostic factors for patients with cervical cancer.

Experimental Study on Inhibition Effects of the XAF1 Gene against Lung Cancer Cell Proliferation

Yang, Wen-Tao,Chen, Dong-Lai,Zhang, Fu-Quan,Xia, Ying-Chen,Zhu, Rong-Ying,Zhou, Duan-Shan,Chen, Yong-Bing Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.18

Objective: To investigate the effect of high expression of XAF1 in vivo or in vitro on lung cancer cell growth and apoptosis. Methods: 1. The A549 human lung cancer cell line was transfected with Ad5/F35 - XAF1, or Ad5/F35 - Null at the same multiplicity of infection (MOI); (hereinafter referred to as transient transfected cell strain); XAF1 gene mRNA and protein expression was detected by reverse transcription polymerase chain reaction (RT-PCR) and Western blotting respectively. 2. Methyl thiazolyl tetrazolium (MTT) and annexin V-FITC/PI double staining were used to detect cell proliferation and apoptosis before and after infection of Ad5/F35 - XAF1 with Western blotting for apoptosis related proteins, caspase 3, caspase - 8 and PARP. 3. After the XAF1 gene was transfected into lung cancer A549 cells by lentiviral vectors, and selected by screening with Blasticidin, reverse transcription polymerase chain reaction (RT-PCR) and Western blotting were applied to detect mRNA and protein expression, to establish a line with a stable high expression of XAF1 (hereinafter referred to as stable expression cell strain). Twenty nude mice were randomly divided into groups A and B, 10 in each group: A549/XAF1 stable expression cell strain was subcutaneously injected in group A, and A549/Ctrl stable cell line stable expression cell strain in group B (control group), to observe transplanted tumor growth in nude mice. Results: The mRNA and protein expression of XAF1 in A549 cells transfected by Ad5/F35 - XAF1 was significantly higher than in the control group. XAF1 mediated by adenovirus vector demonstrated a dose dependent inhibition of lung cancer cell proliferation and induction of apoptosis. This was accompanied by cleavage of caspase -3, -8, -9 and PARP, suggesting activation of intrinsic or extrinsic apoptotic pathways. A cell strain of lung cancer highly expressing XAF1 was established, and this demonstrated delayed tumor growth after transplantation in vivo. Conclusion: Adenovirus mediated XAF1 gene expression could inhibit proliferation and induce apoptosis in lung cancer cells in vitro; highly stable expression of XAF1 could also significantly inhibit the growth of transplanted tumors in nude mouse, with no obvious adverse reactions observed. Therefore, the XAF1 gene could become a new target for lung cancer treatment.

Inclined Slice Method to Earth Pressure of Narrow Cohesionless Backfill against Rigid Walls under Various Displacement Modes

Yu-jian Lin,Fu-quan Chen,Jun-tao Yang 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.4

The displacement modes of retaining walls in engineering are complicated, and the backfill behind retaining walls is often narrow. Failure mechanisms of soils under various displacement modes of retaining walls have not been clarified yet in previous studies. According to results of the finite element limit analysis, multiple sliding surfaces were observed developing reflectively between interfaces on both sides in the active limit state. In rotational displacement modes, some layers of soil near the rotated point maintained in the non-limit state which was not considered in the previous studies. Based on numerical analysis results, failure wedges were divided into differential soil slice elements by an inclined slice method. An analytical model was established to estimate the earth pressure of the narrow backfill under various displacement modes using the limit equilibrium method. The calculated results are consistent with the data gathered from previous tests. Compared with previous studies, the proposed method can reflect failure mechanisms of the narrow backfill and be adapted to various displacement modes of the retaining wall. The accuracy of the calculation results is high in the non-limit state soil layer. In addition, the boundary criterion between the narrow and semi-limit backfills was determined. Based on extensive parametric studies, it can be concluded that increasing the soil-wall interface friction and decreasing the backfill area would be conducive to decreasing the earth pressure and the depth of resultant application point.

Active Earth Pressure of Narrow Backfill against Inverted T-Type Retaining Walls Rotating about the Heel

Yan-Bin Zhang,Fu-Quan Chen,Yu-Jian Lin,Hao-Biao Chen 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.4

Inverted T-type retaining walls are commonly used in subgrade or slope support engineering, which inevitably satisfies a narrow backfill. Using the classical earth pressure calculation method in a narrow-backfill case causes an inevitable error. The current narrow-backfill earth pressure theory does not apply to inverted T-type retaining walls. In this study, the failure mechanism in a narrow backfill when the inverted T-type retaining wall rotates about the heel is investigated using adaptive finite element analysis method. Numerical analysis reveals multiple sliding surfaces. A theoretical model for calculating earth pressure using difference and limit equilibrium methods is proposed. The proposed model is suitable for more complex conditions, including narrow backfill, irregular ground, and non-uniform overload, than previous models. Parameter analysis reveals that the cross-sectional area of the plastic zone and active earth pressure have a positive correlation. Further, the interface friction influences the decrease in active earth pressure. Fitting formulas for assessing the cases of long and short heel and the critical size of backfill width are presented to facilitate practitioners to evaluate the backfill.

Active Earth Pressure against Cantilever Retaining Walls with a Long Relief Shelf in Rotation about the Top

Yun Que,Xue-feng Gui,Fu-Quan Chen 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.6

A cantilever retaining wall with a long relief shelf (CRW-LRS) is a particular type of retaining wall, but no studies have yet reported on rotation about the top of this type of retaining wall. This work studied failure mechanisms in semi-infinite non-cohesive soils in rotation about the top using the finite element elastoplastic analysis method (FEEA). By considering the influence of both the relief shelf and rotational stress from the soil, a formula for calculating the active earth pressure (Ea) was developed using the horizontal differential layer limit analysis method. Four different parameters were studied, i.e., unloading plate’s geometric conditions, heel length and the internal friction angle of the backfill, in terms of their influence on the Eadistribution, resultant force etc. The lowest Ea was found when the relief shelf’ relative position m = 0.4.

Characteristics of wind loading on internal surface and its effect on wind-induced responses of a super-large natural-draught cooling tower

Yun-feng Zou,Zheng-yi Fu,Xu-hui He,Hai-quan Jing,Ling-yao Li,Hua-wei Niu,Zheng-qing Chen 한국풍공학회 2019 Wind and Structures, An International Journal (WAS Vol.29 No.4

Wind loading is one of important loadings that should be considered in the design of large hyperbolic natural-draught cooling towers. Both external and internal surfaces of cooling tower are under the action of wind loading for cooling circulating water. In the previous studies, the wind loads on the external surface attracted concernedly attention, while the study on the internal surface was relatively ware. In the present study, the wind pressure on the internal surface of a 220 m high cooling tower is measured through wind tunnel testing, and the effect of ventilation rate of the packing layer on internal pressure is a major concern. The characteristics of internal wind pressure distribution and its effect on wind-induced responses calculated by finite element method are investigated. The results indicate that the wind loading on internal surface of the cooling tower behaves remarkable three-dimensional effect, and the pressure coefficient varies along both of height and circumferential directions. The non-uniformity is particularly strong during the construction stage. Analysis results of the effect of internal pressure on wind-induced responses show that the size and distribution characteristics of internal pressure will have some influence on wind-induced response, however, the outer pressure plays a dominant role in the wind-induced response of cooling tower, and the contribution of internal pressure to the response is small.

Responses of Buried Pipelines to Tunnelling Underneath Considering Effect of Gap Formation: an Analytical Approach

Bing-qiang Zhang,Qi-wen Chen,Feng-wen Lai,Fu-Quan Chen,Bin-bin Qi 대한토목학회 2024 KSCE Journal of Civil Engineering Vol.28 No.1

A gap formation underneath pipelines could be observed during tunneling beneath existing buried pipelines, thus altering the pipeline-soil interaction behavior. However, the most existing analytical approaches typically do a full contact assumption for brevity. For such purpose, we aim to present an analytical approach coupling the effect of gap formation underneath pipelines by considering the buried pipeline as an Euler-Bernoulli beam on tensionless foundation. The pipeline can be divided into three segments according to pipeline-soil interaction behavior, and then the bending behaviors of each segment are formulated. The deflection and bending moment of the pipeline caused by tunnelling underneath from the proposed approach are compared and validated with centrifuge testing data and existing analytical solutions. The effects of pipeline-soil stiffness ratio, pipeline buried depth, tunnel buried depth, tunneling induced volume loss, and tunnel-pipeline intersection angle on the pipeline responses are further discussed. The results indicate that gap formation underneath pipeline can be observed indeed for shallowly buried pipeline and/or larger pipeline-soil stiffness ratio. The proposed analytical approach provides a theoretical guideline to predict the responses of existing pipelines to tunnelling underneath.