6585844978

Bułgaria 20

Table 1

	Hammer		Immobile	H 0	d s
Type of the tube-tip	Mass of the rammer	Height of dropping	mass of atrlking device	Diameter of rods	Type of rods
	kg	cm	kg	TPTP	-
Light conical	20±0,2	25*0,25	5-10	22	compact
Heavy conical Super heavy	50±Ó,5	50±0,5 A	80 -180	32	compact or ho Ho w
conical	60±0,6	80-0,8	100 -150	42	hollow
Tubular	63,2±0,6	76,2±0,8	20-50	42-50	hollow

sistance. The smali manometer is switch-ed off wlth the atd of a valve when the pressure is above the upper limit of its scalę.

Irrespective of the double .manometers for reading the results this penetrometer is suppliea with two self-recording manometers which drew the diagrams of the tip and total resistance.

Durlng the whole time of operation, the problem was the anchorlng of the static penetrometer. Bven in the morę recent times when the modern penetrometers were imported in this oountry from USSR and Holland the necessity of anohoring is an impediment. Anohoring with anchor dr i lis is not always effioient. While in test-ing tailing dumps with poor geomechanic-al properties light eąuipment was neces-sary, in the other cases we resorted to heavier equipment with artificielly in-creased dead load. With the most modern penetrometers used in this country the results for the tip resistance and the skin friotion are obtained after a ten-siometric pattern. The older models of the static penetrometers still operate with common "protective cone" as the results are read either on manometers or are automatically recorded on a tape me-chanioally.

2.2 Dynamie penetrometers

According to the Bulgarian State Standard 899^-71 "Foundations of Buildlngs and Struotures. Dynamie penetrometer for testing foundation soils. General tech-nical requirementsⁿf the dynamie penetrometer should comprise the following partsi

-    tip (tubular or eonieal)

-    rods

-    rammer

-    measur ing applianoe.

The conical tip sould be madę of Steel and be ligit, heavy or super heavy type, with shape and size ahown on Fig. 1.

Fig. 1. Conical tip

a) light type, b) heavy type, c) super

heavy type.

The tube-tip is madę of steel and has the spahe and dimensions according to the standard penetrometer. The dimensions of the rods and the rammer should be with parameters and deviations as shown on Table 1.

The measuring device should provide far measuring the depth of penetration of the tip into the soil at definite number of strokes of rammer or the number of the strokes for a definite depth of penetration.

The technioal requirements pointed out, had to be implemented into a oonstruo-tion. The operation with penetrometers imported in this country was unhandy.

The indispensability of preliminary dr i 11 ing and in some cases of strengthen-ing the drill walls as well as other features of the instruments restrioted their application. In many oases the