Stability of coal pillar in gob-side entry driving under unstable overlying strata and its coupling support control technique

Considering the situation that it is difficult to control the stability of narrow coal pillar in gob-side entry driving under unstable overlying strata, the finite difference numerical simulation method was adopted to analyze the inner stress distribution and its evolution regularity, as well as the deformation characteristics of narrow coal pillar in gob-side entry driving, in the whole process from entry driving of last working face to the present working face mining. A new method of narrow coal pillar control based on the triune coupling support technique (TCST), which includes that high-strength prestressed thread steel bolt is used to strain the coal on the goaf side, and that short bolt to control the integrity of global displacement zone in coal pillar on the entry side, and that long grouting cable to fix anchor point to constrain the bed separation between global displacement zone and fixed zone, is thereby generated and applied to the field production. The result indicates that after entry excavating along the gob under unstable overlying strata, the supporting structure left on the gob side of narrow coal pillar is basically invalid to maintain the coal-pillar stability, and the large deformation of the pillar on the gob side is evident. Except for the significant dynamic pressure appearing in the coal mining of last working face and overlying strata stabilizing process, the stress variation inside the coal pillar in other stages are rather steady, however, the stress expansion is obvious and the coal pillar continues to deform. Once the gob-side entry driving is completed, a global displacement zone on the entry side appears in the shallow part of the pillar, whereas, a relatively steady fixed zone staying almost still in gob-side entry driving and present working face mining is found in the deep part of the pillar. The application of TCST can not only avoid the failure of pillar supporting structure, but exert the supporting capacity of the bolting structure left in the pillar of last sublevel entry, thus to jointly maintain the stability of coal pillar.

Sodium Tanshinone Ⅱ A Sulfonate Injection as Adjuvant Treatment for Unstable Angina Pectoris: A Meta-Analysis of 17 Randomized Controlled Trials

Objective： To systematically evaluate the effectiveness and safety of Sodium Tanshinone ⅡA Sulfonate Injection（STS） as one adjuvant therapy for treating unstable angina pectoris（UAP）. Methods： Randomized controlled trials（RCTs） of UAP treated by STS were searched in the China National Knowledge Infrastructure Database（CNKI）, VIP Database for Chinese Technical Periodicals（VIP）, Wanfang Database, the Chinese Biomedical Literature Database（CBM）, Web of Science, the Cochrane Library, Embase, and Pub Med, which from inception to January, 2016. The Cochrane Risk Assessment Tool was used to evaluate the methodological quality of the RCTs. The Review Manager 5.3 software was used to conduct the metaanalysis. Results： The results showed that 17 RCTs involving 1,372 patients were included. The meta-analysis indicated that the combined use of STS and Western medicine（WM） in the treatment of UAP can obviously improve the total effective rate [risk ratio（RR）=1.31, 95% confidence interval（CI）（1.24,1.39）, P〈0.0001], and the total effective rate of electrocardiogram [RR=1.43, 95% CI（1.30,1.56）, P〈0.0001], decrease the level of CRP [mean difference（MD）=–3.06, 95%CI（–3.85, –2.27）, P〈0.00001], fibrinogen [MD=–1.03, 95% CI（–1.16, –0.89）, P〈0.00001], and whole blood high shear viscosity [MD=–0.70, 95% CI（–0.92, –0.49）, P〈0.00001]. Additionally, the occurrence of adverse drug reaction of the experimental group was significantly higher than that of the control group [RR=3.57, 95% CI（1.28, 9.94）, P〈0.05]. Conclusions： Compared with WM, the combined use of STS was more effective.