Determining the influencing factors of preferential flow in ground fissures for coal mine dump eco-engineering

Ground fissures (GF), appearing in front of dumps, are one of the most obvious and harmful geological hazards in coal mining areas. Studying preferential flow and its influencing factors in the ground fissures of dumps may provide basic scientific support for understanding the rapid movement of water and vegetation restoration and reconstruction in mining areas. Based on field surveys of ground fissures, three typical ground fissures were selected in the studied dump. The morphological characteristics of preferential flow for ground fissures were determined through field dye tracing, laboratory experiments, and image processing technology. The results indicated that the lengths of the three ground fissures ranged from 104.84 cm to 120.83 cm, and the widths ranged from 2.86 cm to 9.85 cm. All of the ground fissure area densities were less than 10%, and the proportion of ground fissure surface area was small in the dump. The maximum fissure depth was 47 cm, and the minimum was 16 cm. The ground fissure widths ranged from 0 cm to 14.98 cm, and the fissure width and fissure width-to-depth ratios decreased with increasing soil depth. The stained area was greater than 90% in the 0–5 cm soil layers of the three fissures, and water movement was dominated by matrix flow. The stained width decreased from 90 cm to 20 cm with increasing soil depth. The preferential flow was mainly concentrated on both sides of the fissure, which was distributed as a “T” shape. The preferential flow stained area ratios were 27.23%, 31.97%, and 30.73%, respectively, and these values decreased with increasing soil depth. The maximum stained depths of the preferential flow among the three fissures were different, and the maximum stained depth of GF II was significantly larger than that of GF I and GF III (P < 0.05). The stained path numbers of the three fissures ranged from 0 to 49. With increasing soil depth, the stained path number first increased and then decreased. The stained path widths of the three fissures ranged from 0 cm to 90 cm. With the increase in soil depth, the stained path width decreased. The stained area ratio was significantly positively correlated with ground fissure width, the ground fissure width-to-depth ratio, soil saturated hydraulic conductivity, soil organic matter, and sand content and was significantly negatively correlated with soil water content and clay content. The stained path number was significantly positively correlated with ground fissure width, the ground fissure width-to-depth ratio, soil saturated hydraulic conductivity and soil organic matter. The stained path width was significantly positively correlated with the ground fissure width-to-depth ratio, soil saturated hydraulic conductivity, soil organic matter and sand content and was significantly negatively correlated with clay content. Plant roots could significantly increase the stained area ratio, stained path number, and width and promote the formation and development of preferential flow.

Crack Coalescence and Failure Patterns in Brittle Rock-Like Specimens with Pre-Existing Fissures under Uniaxial Loading: Experimental Studies

In practical engineering, the joints or fissures with similar characteristics are commonly found in natural rocks, they decrease the mechanics properties of the rock mass and also can be seen as a source of initiation of new discontinuities. The previous studies (experimental or numerical) has promoted the understanding of coalescence patterns or failure process obtained from brittle specimens which contain single, two or three fissures. However, the failure characteristics of multi-fissure specimens has not been studied comprehensively. In this paper, the crack coalescence pattern and failure mode of the rock-like materials with multi-fissures have been explored. Based on the experiment results, under unaxial compression, we found that the coalescence modes between fissures can be generally classified into three categories: T/S/M pattern. Moreover, due to the difference of inclination angle and fissure numbers, the specimens present different failure mode. Careful examination all of specimens, the failure mode can be classified into 4 categories: Mix failure model(shear+splitting), Shear failure, Stepped path, Intact failure.

Evaluation of Reinforcement Effects for Earth Cliff of Jiaohe Ancient City

The author adopted an in-situ test method of artificial arthquake survey to evaluate reinforcement effects of fissure grouting for earth cliff of Jiaohe ancient city in China. Based on field testing results of three fissures with different characteristics, we compared previous earth cliffs with reinforcement ones by means of grouting. Analysis results show that it is feasible to reinforce cliff by means of the composite method reported by authors, which jointly applies the grouting of Polystyrene (PS) material and the anchoring technology for fissure earth-cliffs of Jiaohe ancient city. Meanwhile, the composite method of reinforcement could obviously improve the integral strength of potentially dangerous cliffs. This means PS material should be a safety media to apply into the reinforcement and the author’s method could be helpful to protect the ruins of Jiaohe ancient city.

Botulinum toxin A in the treatment of anal fissure

Background. This paper presents our first experience in the treatment of primary anal fissure by injection of botulinum A toxin into the internal sphincter. Methods. The study group of the retrospective study included 12 outpatients (8 females and 4 males), mean age 42 (range 18-60). During the period 2000-2003, after unsuccessful conservative treatment, patients were treated with the injections of botulinum A toxin, 100 units on both sides of the anal fissure laterally into the internal anal sphincter (50 units on either side). The patients were clinically evaluated 3, 7, and 30 days, and 3 and 6 months after the treatment. Results. Three fissures had healed after a month, and seven after 3 months. Two remained unhealed, but asymptomatic. There was no incontinence of flatus or faeces after 3 months of the treatment. After temporary healing, two fissures relapsed after 6 months, and these patients had the adequate tonus of the anal sphincter muscles. Except for the temporary incontinence, there were neither other side-efects, nor serious complications. Conclusion. Injection of botulinum A toxin achieved good results in the treatment of anal fissure. The appropriate use makes this method safe as an alternative to surgical treatment of anal fissure.

Microsurgical anatomy of the veins of the posterior fossa

✓ The microsurgical anatomy of the veins of the posterior fossa was defined in 25 cadavers. These veins are divided into four groups: superficial, deep, brain-stem, and bridging veins. The superficial veins are divided on the basis of which of the three cortical surfaces they drain: the tentorial surface, which faces the tentorium and is exposed in a supracerebellar approach, is drained by the superior hemispheric and vermian veins; the suboccipital surface, which is below and between the lateral and sigmoid sinuses and is exposed in a wide suboccipital craniectomy, is drained by the inferior hemispheric and inferior vermian veins; and the petrosal surface, which faces forward toward the posterior surface of the petrous bone and is retracted to expose the cerebellopontine angle, is drained by the anterior hemispheric veins. The deep veins course in the three fissures between the cerebellum and the brain stem, and on the three cerebellar peduncles. The major deep veins in the fissures between the cerebellum and brain stem are the veins of the cerebellomesencephalic, cerebellomedullary, and cerebellopontine fissures, and those on the cerebellar peduncles are the veins of the superior, middle, and inferior cerebellar peduncles. The veins of the brain stem are named on the basis of whether they drain the midbrain, pons, or medulla. The veins of the posterior fossa terminate as bridging veins, which collect into three groups: a galenic group which drains into the vein of Galen; a petrosal group which drains into the petrosal sinuses; and a tentorial group which drains into the tentorial sinuses near the torcula.